Unpredictable behaviour when creating custom tags

[Cybirian]

When creating a custom tag, the moment I click "Add" other tag values are wiped clean including the cover art.
I can't figure out what exactly is being affected but it looks like the title, the genre, the year, and the cover art. But some times other tags are also wiped, Very rarely nothing happens... but touching that "Add" button somehow messes things up in unpredictable ways.

Also, I'm unable to recreate the exact conditions but sometimes when I create the custom tag it freezes that tag and I'm unable to delete it by clicking the trash button, Then by changing a different tag's value and applying the changes it unfreezes the custom tag and only then I'm able to delete it.

It seems that it has something to do with the prompt window that's showing up when creating a custom tag. in fact it seems that any prompt somehow affects the memory and wipes out something. Even adding lyrics in the lyrics prompt and applying changes does nothing. the lyrics are just wiped away.

UPDATE - I'm not sure but I think it has something to do with OGG files.
Tried doing all the things above with mp3 files and so far they don't seem to be getting corrupted.