Why don't I see a collection on my Collections page? I've heard it exists or I had it before!

A collection will show up on your Collection's page once you've looted an item from it for the first time or if someone sends you your first item for that collection.

If you happen to give away the last item in a collection before vaulting an entire set of that particular collection, it sometimes causes the Collection to disappear from your Collections page. This doesn't happen 100% of the time. Some of my empty collections that I haven't vaulted yet are still showing up there. Other ones disappeared, but of course I don't have a screenshot of that to show becaue there's... nothing to show!

Here's my comprehensive list of Collections, collection items and vault bonuses.