This is an issue I have encountered several times now: while searching the stamp catalog, it sometimes won't allow me to delete the searched term or the filter tag, so I cannot access any other stamps.

In this example I had previously used the fey pack. Then I wanted to find the stamps "obsidian rocks". They are not in the fey pack, thus nothing showed - so far, so normal. I then tried to delete the tag filter - I clicked the x (several times), nothing happened. I tried to delete the search term "obsi" - didn't work either. I closed the stamp catalog and reopened it (3 times) - nothing, just frozen. In the end, I had to safe the map, close it and reopen it.