"
Audio Transition Point..." is only for audio.
For stinger without Track Matte this option changes its name to "Transition Point..." i.e. without "audio". Thus, while stinger animation plays - the scene below can be changed at any given time or frame.
Stinger itself can has alpha channel. Some stringer transitions can be designed to travel from corner to corner until whole screen will be filled. Then transition happens (whole screen is covered by overlaying stinger - you can safely switch scene that is below) and stinger again travels but backwards from corner to corner (like screen was brushed and then washed).
If you are using only track matte ("Mask Only") - you need to design track matte that goes from black (scene "A") to white (scene "B"). And then you can specify when audio will switch.
If you want to use track matte, stinger and stinger has alpha channel (transparency) then you need to align all animations in one media file (side by side and in time). Example of such stinger (see below) is variation of
https://obsproject.com/forum/threads/stinger-dont-work.144329/post-529599
Attachment: ~36KB to download.
CRC of the "stinger_and_track_matte_example_obs_v30_0_0.zip" archive, MD5:F48CE361F5699F64613054A3BD3B5C13
In the archive you will find media files that were used during making of "stinger_with_track_matte_for_obs.mov" example file (that itself represents simple "wiper" effect that starts from right side of the screen).