P: When trying to add files to Collections I get this error: ?:0: attempt to compare two nil values

this bug seems to disappear when the order the pictures in the grid is NOT "personalised"

Why conversations get merged: 

https://feedback.photoshop.com/conversations/lightroom-classic/lightroom-auto-import-to-folders-organized-by-date/5f5f44f14b561a3d422ab0ba?commentId=5f5f48984b561a3d422bdf45

Just today, whenever I try to drag photos into a collection, I get the error  "An internal error has occurred: ?:0: attempt to compare two nil values".

It was working fine half an hour ago, I'd added about 20 photos to the collection, and then it just suddenly stopped working. Eventually, I realised that the problem was with one specific collection, and tried deleting and recreating the collection, which fixed the problem. Just leaving this here in case anyone else has the same problem....

(Lightroom Classic 10.0, Build 202010011851-ef6045e0)

I'm getting this error message when trying to add an image to the quick collection. I used it yesterday and it was working fine. I tried to remove and import the image again but got the same error. 

I have same problem after moving to Big Sur

I'm having same problem after installation of Big Sur

This works for me too. Thanks!

A Quick Collection fix that worked for me.  Like others, any attempt to add an item to the quick collection with a B or clicking the little dot at the top right of the image resulted in the error described above.  Changing the order of the collection did not work.  I opened my quick collection and saved all images as a new collection so I would have my picks.  Then I removed all items from the quick collection.  I went back to my original problem collection and was able to add to the Quick Collection with no issues.   

Same problem here also on a MAC. It is 21 days later now. Clearly not fixed yet. Would be nice if they do not release new versions without proper testing first. 

Thank you Parker and everyone. I had misunderstood and had changed the source folder to anything but custom initially. When I changed the target collection to anything but custom order, it worked. Thanks for your assistance!