When you "deleted the library", how did you do that?
Did you just delete the contents of the Library by selecting all records and deleting? I ask because it isn't possible to delete the default Library in MC. So if you were using a Library stored in the default location, which is by design the default Library, then you could not have deleted it. If you created a new Library in a non-default location, then that could be deleted, which would completely remove everything related to the Library.
If you just selected all the records in the Library and deleted them, that doesn't delete all contents of the Library. MC maintains a "Removed Database" in its Library, which is a record of all items that had been imported at some time, and later deleted. If a file is later imported again, MC uses the metadata from the Removed Database for that item.
So, importing a file and finding that it has incorrect metadata, then deleting it, fixing the tags in the file, and then re-importing it will result in the old, bad metadata being used. I mentioned that back here:
Okay, you are deleting incorrect metadata out of the files before you import them into MC. That is fine. If you have already imported them into MC, then delete them from MC, then delete the metadata externally, then import them, that won't work as MC remembers metadata for previously imported and later deleted files. That can be fixed of course, but requires extra steps.
The extra steps that are required to fix the metadata are to delete the records in the "Removed Database". That is easy to do. Just create a View that shows all media types (uncheck the "Use parent scheme rules for file display"), restrict the View to the Removed Database ("Set rules for file display" > Modify Rules > Limit database to > Removed), then delete the affected movies from MC again, find any movies you have deleted in the Removed Database (or set a rule in the View to only show files that do not exist in the Library), then delete the records from the Removed Database. You would then be able to import the files again and MC would use the filename and tags in the file to identify the program.
The alternative is to use clear Library function and start all over again. You can do that by selecting the Library under Playing Now, and then clicking the "Clear Library" button. That removes everything from the library so that it is empty, but that would mean that you have to start again importing everything. Usually not a good option. If you want to do that, then for those movies that have the correct metadata, make sure that you write the correct data to the file tags first. See below.
Windows does not show all tags that MC uses, not by a long shot. It also uses slightly different naming for some tags, such as using "Title" where MC uses [Name]. If you want to see all tags actually in the files you could use a third party application, or you could look at the "Options > Library & Folders > Manage Library Fields" dialogue, and select "Show only field saved in tags". That will show you which Library field are saved to file tags by MC when they change. You should also look at the "Tag Dump" area in the MC Tag Window, which will show the fields MC has saved to the file, plus any tags in the file that MC hasn't imported into its Library.
If you want MC to write updated metadata to tags in the file, make sure that the setting "Options > General > Importing & Tagging > Update tags when file info changes" is checked. To update tags for files that have already been imported and had metadata corrected, select all files, right-click on one, and then select "Library Tools > Update tags (from library)". Note that MC will only write those Library fields to tags in the file that have been set to be saved, as defined in the "Options > Library & Folders > Manage Library Fields" dialogue. But the defaults should be fine for what you are doing.
However, note that MC doesn't write tags to a file for video files. It writes them to the Sidecar XML file. So when you check in Windows, the tags that you have cleared will remain empty.Nothing about "Hancock" being changed to "Hancock 2" makes sense. That just doesn't happen in normal use of MC. Particularly if a file has already been imported into MC, as Auto Import won't change metadata for an existing file unless tags have been changed in the file by an external process, and Auto Import was set to "Update for external changes", which it usually is. We are missing some information required to work that issue out,
such as perhaps Kodi or Plex being run at some time, and one of those two programs updating the Title tag to "Hancock 2", which will then flow into MC when Auto Import is next run.
