Hi@rockmond,
Based on the issue that you mentioned, do you want to remove the item from the gallery or the collection?
The first formula you provided only remove the item from the gallery that won't remove item from the collection. If you want to remove a item from the gallery and the same to the collection, you should make sure to find the primary key in your data source.
I tested the Remove() function seems that there is something wrong when working with the Gallery.Selected record. Please modify the formula as below
Remove(collChallenges,LookUp(collChallenges,ID=ChallNewCollectionGallery.Selected.ID))
Note: ID is a normal primary key in the data source, you can replace it with yours in the collChallenges.
Best Regards,
Qi