Ok, finally got home and gave it a try... I deleted JRemote and re-installed it from the App store. Upon reconnecting to MC, via the access key, the left-hand choices are now reduced to just "Streaming" and "Remote". No "Audio", "Images", "Video", or "Playlist" choices at all!
Checking against JRemote 3.29 on the iPhone, connecting to the same running MC instance, everything is still working normally.
Since nothing has changed on the MC instance, and given the re-installation, this seems like something amiss with JRemote 3.30.
Other thoughts or experiments I should try?
[Update 1: In case it comes up, the same result occurs if I delete the server and re-connect using IP address. I do have authentication required; I'll try disabling that as well in case that makes any difference.]
[Update 2: No difference with authentication turned off.]
[Update 3: I stopped and re-started MC on the PC, and also killed and re-started JRemote on the iPad. I'm now back to having "Audio", "Images", etc choices on the left, but selecting any of those results in an empty list of subsequent choices; so, back to the original behavior I described.]