For 5.0.3 (as of build 2622) you'll need to explicitly enable to update all files before you can add an extended tag for a multi-select. This will still overwrite any existing tags. For 5.0.4 a solution will be worked on to solve that bug.

Hi,
Main issue is that till you it was just possibility and as there was only few questions regarding Extended tags and none regarding Multi files editing it was just sitting there without enough data and workable solution.

Also as Extended tags are available in our API for any developer out there willing to make complex/advanced extended tags editor it was open.

Only downside, that it was you that gave us enough reasons to elevate and push it further to solution.

I'm not sure it's the same issue, that bug doesn't reference all tags being deleted, but if you're confident it's all part of the same thing then I won't argue!

What's concerning though is that the bug has been there since September 2020, market "urgent" and "major", and it hasn't been resolved... it's the kind of bug that people won't know is messing with their music until it's too late so this is worrying.

It's tracked in a different bug: https://www.ventismedia.com/mantis/view.php?id=16924

Thanks for reporting Lowlander.

It has been marked as resolved by michal as the same problem as the one he linked to.

But it is not the same problem, it's a lot worse!

Thanks for reporting, added as: https://www.ventismedia.com/mantis/view.php?id=19059

Bit of a disaster here

Let's say you have an album and you have used Extended Tags to set some tags that MM doesn't support.

If you then select multiple files and go to Extended Tags to set a tag that applies to the whole album, it will do that, but it will also wipe all other extended tags

This needs to be fixed ASAP please.