Just checked WMM and it's fine. Next thought is the font used for the subtitles. I bleeped the use of the word "Skype", so that's not it, and i carefully avoid any appearance of trademarked logos in videos, to the extent of sticking labels over clothing.
Unfortunately i don't feel it's likely that i will get an answer from YouTube itself, so i'll just have to keep trying and see what happens.
The chief problem is of course not monetisation as such because it's virtually impossible to derive an income from YT advertising alone, but the problem of what happens if the terms of service are violated by it.
No video today of course (except for tonight's, which is the one causing the problem and apparently won't work until this evening):