When I upload a video recorded in AMD Adrenaline Edition to Vegas it turns green.
Please post Mediainfo on one of your problem files. Instructions here https://www.vegascreativesoftware.info/us/forum/faq-how-to-post-mediainfo-and-vegas-pro-file-properties--104561/
The media is most likely not supported; are there other settings you can use to save it in your software? If 8-bit h264/AVC is a choice try that.
I know that back in the day, when users would bypass so4compoundplug.dll in internal settings, it would break compatibility with 10 bit media, causing a green screen when 10 bit files were loaded.
My Geforce captures render from Vegas partially slower than any other video I use, they're variable but so are my phone clips that render at a 'normal' speed & there's nothing in Geforce I can change to alter that.. Also if I upload a capture video straight on the forum it uploads slower than an edited & rendered vid does. (I edit captured vids anyway, but I do it also to make upload quicker)
First render is the captured vid second render is the rendered vid rendered again.
This doesn't bother me it's just something about the nature of these captures, so it would be interesting to see the MediaInfo of @lucas-b4059 Adrenaline videos.
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As an example this is a phone clip, as you can see it's 'quite' variable but renders only fractionally slower than the rendered clip & I'd say comparatively faster than the captured vid.