dragging files from finder into a collection does not add them to the collection, it adds them to the general fonts inactive category. On windows I can drag the files into a collection and they get added to that collection.
Hello @pjos, thank you for your post and welcome to the forum 
A few questions can help to better understand what’s going on:
Has it been like this on MacOS every since you installed the app or is this a recent development?
Does this happen when you try to drop OTF and TTF font files into any collection, including the ones you’ve created manually?
Thank you again,
Hi! I have the same issue with all kind of fonts (otf and ttf). Drugging in the manually created collections from Finder does not work.
MacOS Sequoia 15.5
Hello @Viklon, thank you for your post and welcome to the forum
Would you happen to remember what changed between when this working and when the issue started occurring?
Thank you again,
@Viklon @pjos thank you for reporting this
Found the cause of the issue, we’ll try to upload the fix asap.
Thank you again,
Thanks for so fast feedback. Looking forward to the resolve.
We have the same problem with 2.22.4…
When can we estimate a solution? My AD kills me. 
Hello Matthias, thank you for your post and welcome to the forum
The new update should be up in the coming weeks, it will ship with a major improvement of a thing we’re working on and will include the above mentioned as well.
Sorry for not being able to provide a more specific deadline and thank you again,