Thanks to Florian for his everlasting will to improve this genius program.
Nevertheless a strange behaviour showed up with the latest update (v2.87a).
Some files won´t show length or bitrate, happens 2 of 4 in my case.
The reason must be some malformed streams (unknown or truncated), but the last version (v2.86) showed at least anything (even if it was wrong, e.g. cbr128 instead of cbr320).
Other programs recognize this as cbr320 files without problems:
see here https://i.imgur.com/VVaVnq6.png
(sorry, cannot embed more than 2 images as new user)
Is there a way to improve this?
What happens after you repaired these files?
The files have various MPEG stream errors — most players can detect such errors and silently re-sync the MPEG stream. With v2.87, I've reimplemented the MP3 info parsing and with that, removed a couple various workarounds for broken files.
I suggest, before posting a bug report, to test the files by yourself for errors using, e.g., MP3val (which also supports fixing those files).
Ok, so that´s clearly the reason for the altered behaviour.
Sorry for the bug report - you´re right it´s not a bug as it doesn´t effect tagging.
Thanks a lot for your help. - Solved.