Library not used during startup

Hi guys,
I use v2.94 under Windows 1903 home. Upon removal of a thrid-party virus checker (and thus reverting to Windows Defender) MP3TAG does not use the library any more after a PC boot. It reads all entries from the original files resulting in about 3 minutes to start for just under 10,000 files. I have already re-installed the application both with and without deletion of the %APPDATA% directory - all to no avail.
I would appreciate any helpfull suggestions.

MP3tag reads all files and compares whether the modification date of the library and that of the files match. If they do, then reading goes much quicker.
If they don't, then a new or updated entry is created.
You do not say anything about included folders (if there are any) or what kind of storage you access (e.g. like the music files being on a NAS) or whether you have cleaned up the library recently. These things.
A reliable judgement whether the library is used or not would be revealed by the sysinternals process explorer.

The files I access reside on an ordinary SATA HD and are distributed among 10 directories under D:<username>\Music\Musik n. All are MP3 files with fixed bitrate.
Mp3tag's library (C:\Users<username>\AppData\Roaming\Mp3tag\data\library\mp3tag.db3) is listed in the process explorer's lower pane. Additionally, when I instruct the application to cleanup the library it apparently does so.

This may be a trivial question, but: have you switched on the library?
Have you set any folders to be included in the library (so that no files outside these folders are added to the library) or no folders so that any loaded files are included.

BTW: if you find that the library is used by MP3tag then the original statement that the library is not used, is at least questionable.

Most certainly I have switched the library on. I have also switched it off and closed Mp3tag, then switched it on again. I have tried both ways to exclude and to not exclude folders as well.
And by the library not being used I was referring to its original purpose of speeding up the startup process (which it still does not do).

I have had a similar experience about which I wrote in the german section of the forum:

I too had a third-party virus scanner and the defender had accidently been activated without me noticing. Disabling the defender and reactivating the third-party virus -scanner resolved the problem for me.

AFAIK the original purpose of the library was to cope also with big collections with even more than 100,000 files.
Before the introduction of the library, only some 50,000 files could be treated in one go.

I can confirm that windows Defender in Win 10 does interfere with the library function.
After adding Avast (Defender disabled) it restored library function (thankfully!)

You can use the defender if you define an exception for mp3tag.exe.

Thanks. I'll try that.

What worked for me after lengthy trials was an exclusion for the process "mp3tag" (without any extensions) in Windows Defender.