Five USPS FirstClassLetters marked as ‘delivered’ in the last month were not delivered

I just got back into football cards and have made 50+ purchases on eBay in the last 2-3 months. Nearly all have been shipped with usps ground advantage, and I haven’t had a single issue. However, I’ve purchased 5 lower-end autographed cards ($5-$15) in the last month, all 5 were shipped in a usps FirstClassLetter, and all 5 were marked as delivered despite never being truly delivered. For context, my apartment complex uses a package delivery service, and that’s what I use as my shipping address. I’ve confirmed multiple times now that my delivery facility did not receive the FirstClassLetters. They also told me they pick up packages from the local usps distribution center. I tried to check there, but there was nobody to help me since it’s not a normal USPS store. My guess is that usps doesn’t actually deliver to my facility. All 5 were marked “out for delivery” from a postal code that is only registered to a (different) USPS distribution center, then they were marked as ‘delivered’ with the same postal code as my delivery facility despite never actually being delivered there.

I’ve already created a missing mail claim for all of them and put my apt address as the forwarding address, and I don’t think I’ll have any issue getting refunds if I can’t recover. That said, i just want my cards lol, and I feel like I have enough info to track these down considering all 5 have had identical tracking updates. I’m thinking they must either be at the distribution center where they were marked “out for delivery”, or the usps location in the same zip as my package delivery facility. Does anybody have any input, or have any of you gone through something similar before? Any USPS workers that might have an idea? Am I dumb? Any input is appreciated.