Collection achievements interface.
I have the same problem, but with the diving achievement… At least you can stay in one map!
I remain at 29/30 in the first DT coin collection because I found a bunch on my own, then followed the Dulfy video to each and every one. But since they disappear once found, I couldn’t tell if not seeing one at the spot meant I wasn’t quite in the right place or if I already had it. After doing the full Dulfy tour in close to two hours, I was still at 29/30 and gave up. Because of that I had no real oomph pushing me to do the next collections.
Give me an indication of which one(s) I’ve found and clues at the LA Exterminator level of difficulty to the ones I haven’t, and I’ll cheerfully spend my time searching them out. Until then, it’s content not worth the bother.