I've made all areas of a shirt hide the body mesh of anyone wearing it, and it looks fine when viewed in the Hide Body Mesh tool interface, but as soon as I leave that, the garment in questing still shows skin texture through it. Is there a setting somewhere else that I'm missing for the shirt?

TYVM in advance for any help...

I tried the shirt in question on a different character, and it worked on that one. The other one was an older CC2 character, not sure what difference that makes, but I have concluded that this is something to do with the CC3 character that I began with, because the shirt works on other CC3 & 2 characters.

...Any ideas?

I guess I'll post to say that I solved this issue by going back and finding an older avatar of the character in question, and re-updating it to reflect the most recent changes.
I still have absolutely no idea what caused this issue, nor how to avoid it in the future.

Im having an issue with the new CC3+ character, and after hiding the body mesh, when closing the tool the clothing in question vanishes and the body part selected to be hidden remains hidden. Im still new and learning, but I also assume this is an issue with newer characters, Ive done the process before without issue.

Yeah, I'm just encountering this with an older character I use in a safety video.
When using a newer avatar, it seems to work but it's bloody annoying as we like to consistently use the same characters in the animations we create.
Has anyone submitted a bug report?
I'll do it when I have a moment.

Hope this will help

https://www.youtube.com/watch?v=ZK_mIXFCAUA
Check this video chapters. I had the same issue.