Since updating LR 4.2 RC (on Mac OS X 10.8.1) yesterday I can't save meta data in photos any more. Cmd+S brings up status bar saying that meta data are being actualized, but in grid view the photos are still shown with meta data to be actualized (arrow down).
Thanks for the info. I am able to reproduce this problem, and I've entered the issue in our bug database. To be clear (because this thread has evolved somewhat from the original posting), this is the problem that I've reported:
When a metadata field (caption) contains a "tab" character, Lightroom erroneously reports that metadata is unsaved, even though in fact the metadata has been saved correctly. Happens with JPEG, does not happen with raw. Happens on both Mac and Win.
(EDIT: I take it back, seems to happen with raw files as well as JPEG.)