I’m just replying to concur that this problem exists. I’m currently cleaning up a manuscript in the scrivenings view; I’ve used a bunch of regexes this morning to get rid of some frequent formatting errors. In the cmd-F find&replace dialogue, the \U case transformation doesn’t work. But according to the the PCRE manual, this flavour of regex implementation simply doesn’t understand the \U transformation command. Cf. manpages.ubuntu.com/manpages/har … ern.3.html
So, it smells like a bug, but it more likely it is a feature. 