when generating masks only certain options do not function properly

[ride5k]

generate masks only, does not seem to detect all faces (as if "first face only" is selected, but it is not)
also skipping empty masks does not seem to work (toggle does not change output)

[kex0]

generate masks only, does not seem to detect all faces (as if "first face only" is selected, but it is not)

The way it works is it creates 1 mask per face, so you have to activate the 'Single mask per image' option if you want to see all faces in one mask.

also skipping empty masks does not seem to work (toggle does not change output)

You're right. It is now fixed in the latest commit 4b77d12

Here's a short video that shows how it works.
https://www.youtube.com/watch?v=NthOWCmoBPA