If I place a mostly transparent text png in vid channel 2, superimposed on a video on vidchannel1, it’s fine, I can see the text and the video.
If however I place a vid in channel 3 and a png on vid channel 4, for some reason the transparency is gone and all I see is the text over a black background.
Can you post a screenshot? I’ve found by trial and error that if I place a transparent .png over a video file with nothing below it, I can weird banding/pixelating issues. There needs to be something below it, even if it’s just a plain black color.