- I'm frequently having to restore the library from a recent backup (which I now save daily) as MC27 periodically opens with maybe only 300 files of my 44,000 plus file library. This never happened with MC25. Is there a setting I need to activate? Didn't do anything when I went from MC24 to MC25, the transition was seamless.
When it opens showing only the 300 tracks, are you sure the others are gone and not just being mis-filed or that you don't have a filter on the view somehow?
Assuming that they're actually gone, the thing I would check first is to go into Auto-Import's settings and turn off Fix Broken Links. It is possible if your files are going offline temporarily (maybe a USB disk is spinning down or acting dumb, or a Network Drive is going offline, or something like that) and the files are being removed from the Library by Auto-Import. Disabling the Fix Broken Links will stop that from happening.
Also, make sure you aren't also running MC25 still in Media Server mode. Sometimes the Startup Settings get kinda confused on update. It generally doesn't automatically update that (allowing you to test out the new version without "fully switching to it").
If you use Media Server, check the Startup Settings for MC27 under Tools > Options > Startup and make sure they're set the way you want, and then either uninstall or UNDO those same settings in MC25. It could be that your Library is getting confused because everything is "in-use" twice while you try to run two separate versions of MC simultaneously.