One of the items listed in the Build 356 updates list states that the Flicker Control issue has been fixed. It is not fixed. I'm still getting the same behavior with the program freezing with audio continuing to play.
Here is a screenshot of my settings, which are totally random. I have no flicker issues until using this setting. It is on a UHD4K clip and playback is Best>Half. The clip is 23 seconds long. I do have the "old" way Vegas uses the spacebar and Enter key for timeline playback/pause.
If you are having this issue, you have to provide more information. Settings, and clip.