Note after getting the 2 video track uncrossed that there is now a gap in the audio.

do you mean this gap?

This is a normal Vegas behaviour when you split an event and makes just the audio fade out/in within a frame. nothing to worry about, it makes a hard cut just sound smoother.

@3POINT - I had an issue I found recently where I could not reply to any topic, plus also access the tool dialog you mention above. I made a separate topic for this and also submitted a support query to magix about it. In the end it seems it was my antivirus program allowing me full access to the forum, which is now solved as I can reply to your comment

Now to describe the issue fully and with images:

• I start with a single clip (0:01:41:09 = 2534 frame) and slip it at at 00:00:18:30 (470 frames)
• 
• I add a transition (Dissolve:Default)
• 
• Center of transition still at the original split location (00:00:18:30 = 470 frames)
• I then remove the transition via the Fx dialog
• 
• The result is the transition is gone, but a cross-fade is left
• 
• I then drag the clip on the right to the right to remove the crossfade
• 
• Note the gap in the audio. Also note that the video at the split is now at 00:00:19:8 (483 frames). It seems that the clip on the left of the transition was stretched by 13 frames. You can see the the video clip on the right has also been stretched by 13 frames by looking at the end of the timeframe, which is now at 00:01:42:10 (2560 frames) = 26 frames longer than I started
• 

@3POINT - It seems that when I try to add a transition to my timeline that it only goes on the video side and not the audio. Note that my media is MP4 video/audio clips and that the ignore grouping button is not enabled, so the transition should be for both like in your example. Not sure why I cannot get a transition added for both video and audio tracks

@John-Callahan That is the normal behaviour on VEGAS. The event is extended when you add a transition to a cut. To change how this will happen, go to Preferences > Edit > Cut-to-overlap conversion. You have "Centered on cut" selected, it's possible to select before or after the cut.

To temporarily allow ungrouping in order to change only the length of the video, hold Shift while dragging the event's edge.

@LdM_Edit - Changing the cut-to-convention does not solve the problem. Dragging the transition to the timeline using the Shift key does not change the behavior as it still only adds the transition to the video track and not the audio. No matter where I drag the transition to, it will only allow me to add to video track. See @3POINT first comment where he shows the transition effecting both video and audio tracks, where my question is why I cannot add the transition to both video and audio, considering they are linked to the same media (MP4).

So, at the moment I can use the transition, but cannot remove it without a lot of work to get it back to the original state. It would be easier to remove the media and readd, but that may also negate other effects I had added such as color grading.

@John-Callahan I said nothing about holding shift while dragging the transition. I said hold shift while dragging the event's edge to temporarily allow ungrouping. This could make easier to restore the event to the desired's length.

If you want to convert a transition to a cut again, put the cursor within the transition, and hold Ctrl while pressing the / key on the numeric keypad.

What @3POINT showed you is what happens when you overlap two video+audio events: VEGAS automatically adds crossfade transitions to both video and audio. You can then change the type of video transition from crossfade to something else.

The situation that you are describing is different. You don't have two video+audio events that overlap, but two video+audio events that are next to each other, which results in a cut. When you add a video transition to a cut, VEGAS extend the length of the video to acomodate the transition. It does not extend the length of the audio because you are only adding a video transition. VEGAS does not know what you want to do with the audio.

You could start with overlaping the events in the first place to create a crossfade for both video and audio, and then easily add or remove transitions by dragging them from the Transitions panel, or by clicking on the icon indicated by @3POINT. Or convert them to a cut as explained before.

It's all explained in the manual.

@John-Callahan  ... I was able to repro how you are applying a dissolve in Vegas Pro - it requires the length of the video events to be shorter in length at the out and in points of the video events to which a transition is being applied. While this may be the method to apply transitions in other video editors, it is not the best approach in Vegas Pro. The best way, as mentioned just above, is to overlap the two events thus creating a dissolve on both video and audio tracks, and then add the transition to the video dissolve. Undoing the dissolve will in no way alter the audio track (well it hasn't for me in some 15 years of using Vegas Pro).

@John-Callahan As mentioned above by the others -

Drag one event (video+audio) over another to create a dissolve .