1. Yes, all 3 audio tracks are there

2. It is an mp4 hevc with 3 AAC LC audio tracks

3. where do i put it? I can do that.

I do have to point out that it was working previously to the upgrade.

https://ufile.io/6myzf file uploaded here.

Mediainfo does show three audio tracks on your file, but I can't I load the file in Vegas Pro 10, 15 or 16. It errors on all three versions. That tells me the first thing to question is the file's codec. Whichever one is used for that file apparently doesn't play nice with Vegas. I don't know how to explain why it works with your version 14, but I recommend exploring a way to use a different codec and see if that gets you anywhere.

Do you mean it doesn't load at all? Or that it only loads the first audio track?

Doesn't load at all. I get an error on all three versions.

sorry did an oopsie with avidemux.

https://uploadfiles.io/lg7bz that test file didn't open at all - this does and shows only the first audio track.

Your new link points to a good file now and I see the issue you describe on VP 15 & 16. I looked at the properties for the file through Vegas and it shows only one audio stream even though Mediainfo shows three. I need to find and load VP 14 to fully test what you see, but I can't do that 'til tomorrow.

Thanks a bunch in advance!

FWIW I just tried it in Vegas 14, I only see 1 stereo audio track, same in Vegas 15 (I don;t have 16)

Settings in obs haven't changed so i really have no idea why it wouldn't work.

Regardless of that...can anybody explain why it doesn't and hopefully how to fix it?

"...can anybody explain why it doesn't and hopefully how to fix it?"

I don't know why Magix Vegas Pro 15 doesn't decode multiple AAC audio tracks from your recording as you expect. Magix Vegas Pro 14 decodes the audio as a number of mono tracks on my machine. It's of little consequence to me, as I would never use a highly compressed encoder such as HEVC for screen capture and later editing in an NLE. For future recording, I'd find a different encoder.

For past recordings, you can us Handbrake to re-encode to AVC, which Vegas handles OK.

Edit: Even though I find redirection to outside sites tedious, Magix doesn't seem interested in hosting media used to communicate support activities on this forum. Thus, the link to youtube. 

Recordings in avc have no audio issues - they straight up don't even open :\

I re-installed VP 14 and I cannot reproduce the condition you see. Like the other two versions I've tried, 15 & 16, 14 imports your file's audio as only one stereo track. I can't imagine how you see multi-audio tracks in your timeline using any Vegas Pro version on the specific file you provided. The only way I can possibly explain what you see is maybe you have your VP 14 preferences set to import stereo audio as dual-mono tracks. If that's not the case, and since VP 14 accomplishes what you want with your audio, perhaps you can use that version to render a multi-audio track .wav, then import that .wav file into your VP 15 project for your audio track(s). I know it's an extra few steps to get what you want, but that's all I got!

This is starting to feel like an obs missetting, but i can't pinpoint where the problem lies. Switching encoder from hevc to avc results in unopenable files for vegas (they still work in vlc). I wish i was more knowleadgeable. I guess i'll try a trial of premiere and see if that handles my files better.

In the meantime i switched to single track audio which will have to do for now.

Is there any place where i can file a bug report since it does have some funky behaviour?

"...can anybody explain why it doesn't and hopefully how to fix it?"

I don't know why Magix Vegas Pro 15 doesn't decode multiple AAC audio tracks from your recording as you expect. Magix Vegas Pro 14 decodes the audio as a number of mono tracks on my machine. It's of little consequence to me, as I would never use a highly compressed encoder such as HEVC for screen capture and later editing in an NLE. For future recording, I'd find a different encoder.

For past recordings, you can us Handbrake to re-encode to AVC, which Vegas handles OK.

Edit: Even though I find redirection to outside sites tedious, Magix doesn't seem interested in hosting media used to communicate support activities on this forum. Thus, the link to youtube. 

Thank you for all the time and effort you put into it, first of all.

Which build of 14 are you using there?

Version 14 Build 270

"...can anybody explain why it doesn't and hopefully how to fix it?"

I don't know why Magix Vegas Pro 15 doesn't decode multiple AAC audio tracks from your recording as you expect. Magix Vegas Pro 14 decodes the audio as a number of mono tracks on my machine. It's of little consequence to me, as I would never use a highly compressed encoder such as HEVC for screen capture and later editing in an NLE. For future recording, I'd find a different encoder.

For past recordings, you can us Handbrake to re-encode to AVC, which Vegas handles OK.

Edit: Even though I find redirection to outside sites tedious, Magix doesn't seem interested in hosting media used to communicate support activities on this forum. Thus, the link to youtube. 

OBS is practically industry-standard for gameplay screen recording and streaming. Most other solutions are similar.

These recording applciations use the GPU Encoders (QSV or NVENC... VCE rarely) to record gameplay while using almost no CPU or GPU power (as a dedicated chip handles this). They encode to H.264 or HEVC... unless you have the option for something less "mainstream" like VP8 or VP9.

Recording to a format like DNxHR or ProRes is not optimal, as that would require too much CPU power during gameplay, which can bottleneck the machine.

Using a Recorder is possible, but it would still mean you have to buy a truckload of storage to facilitate this. HEVC is used for its Quality:Space ratio, which is excellent. You can always Transcode it out to ProRes or DNxHR later. It's just gamplay footage/screen recordings, not a feature film :-P

VEGAS Pro 14 may decode the Audio Correctly, but the editing performance will be tragic, because it lacks the QSV Decode Acceleration that v15/16 have. It also has Broken GPU support on modern boards, like Nvidia Pascal chips. I wouldn't even consider it an option, honestly.

OP can try using something like Resolve and transcoding to Grass Valley HQX in AVI, and then using their free Encoder/Decoder to load that into VEGAS Pro and see if the Audio Shows up properly. The files will be huge, though...