Hi Matt.
I had been editing photos for a wedding on Lr Mobile on the iPad for a few weeks when Lightroom 5.5 and Lr Mobile for iPhone was released. Once those downloads were available I updated the app on the iPad, installed the app on my iPhone, and updated to 5.5 via Adobe CC on my desktop. When I next opened Lr Mobile on the iPad all photos that I had edited previously started to revert back to their unedited (post import) state as that synced. Before other collections I was working on hit the same issue, I stopped syncing those, and even tried completely re-syncing the collection where I was losing edits, but overnight (i.e. by the time a full sync had occurred) my files were back to their unedited state on both the iPad AND the desktop. I had only added a 3 star rating to the files on the desktop (which never made it to the iPad) but hadn't made any adjustments in the develop module at all. My only recovery mechanism was to notice that the snapshot for the edited files had the edits I had made marked as From Lr Mobile so on the desktop I individually reverted all 560 or so photos to the appropriate snapshot.
I can't be sure that a sync of the ratings change had happened, but I'm pretty sure the desktop and iPad were fully in sync in terms of adjustments by the time I updated the desktop and/or mobile app.
I have a few other collections that I last edited in 5.4 that I need to return to in 5.5, and the same issue may well occur for those - I'll keep you informed. In the meantime the collection in question here is in the catalog I sent you for the re-order issue. This collection is Weddings > Yvonne & Dan.
Ronan