Mirillis Action's MP4 codec (regular or NVIDIA NVENC) doesn't work properly with Sony Vegas Pro 11/12/13. This is due to an issue with the compoundplug.dll plugin. Now, most people would say to simply delete and/or replace it with another plugin, most notably qt7plug.dll. This is not acceptable to me. Why you may ask? Simple: older recordings from Action dating back to November 2014 import flawlessly. It was sometime down the line after numerous updates that suddenly the Action MP4 codec became incompatible.
In addition to that, ShadowPlay (NVIDIA NVENC) currently, and always has imported flawlessly. Same with Open Broadcaster (NVIDIA NVENC), Bandicam (NVIDIA NVENC) and Dxtory (MP4 codec). Point being, all those programs import their MP4's into Sony Vegas Pro utilizing the compoundplug.dll plugin without any issue whatsoever. Mirillis Action used too as well. I have no idea what changed, but something did. Something that makes it incompatible with Vegas Pro's compoundplug.dll.
The "fixes" people post (switching to qt7plug.dll) is not an option. The performance during playback and editing utilizing that plugin is abysmal. Even using the mcmp4plug2.dll plugin (although looks fine on the surface) has issues with the last portion of any given clip being blacked out.
It used to be that Vegas Pro would take ages to build the peaks for Action recordings, but would import without problems - to only importing the audio tracks quickly with no video. That, or it imports everything, but the audio is cut off halfway through the clip.
I'm annoyed because with Time-Shift, and the ability to record the microphone into a separate audio track, I was on the brink of using it exclusively and showing ShadowPlay the door. Unfortunately, this issue prevents that, since all recordings from Mirillis Action (excluding AVI) is completely unusable and Time-Shift is only compatible with the MP4 codecs.
Not sure how this can be addressed, but it is something (as a paying customer) I would love to see addressed and soon.