Hello,
It's hard to say without debugging it. I tested our main Document Editor demo and the RichTextBoxExtended.OnFontFamilyExecute method there only gets called with Commit when clicking an item.
Note that in our OnFontFamilyCanExecute method we also set: e.CanExecute = true;
Please check that out and if you still can't figure out the problem, build a new simple sample project that shows the issue and send that to our support address. Exclude any bin/obj folders from the ZIP you send and rename the .zip file extension so it doesn't get spam blocked. Thanks!