Finally got around to upgrading my forum from XF 2.1.5 or so to 2.1.9. Auto-upgrade didn't work, so I had to do it manually. I logged in to XF customer area, downloaded upgrade package, unzipped it, uploaded files to the server, visited /install folder and clicked button to upgrade. ACP says I'm now running 2.1.9, but file health check now claims 585 files have unexpected results. I've re-uploaded all 585 files that it complained about, but running file check again, I get the same error on the same 585 files. How can I fix this?.