I've had similar problems, but with USPS. I bought a bottle of Dark Titebond II Glue from Amazon about this time last year. I needed it for a special project that needed to be finished within a few days. On the scheduled arrival day I checked the mailbox at 10 am, then again at 1 pm. When I tracked the package at 1 PM it said that it had been delivered at 11:45 AM, so I went and looked in the mailbox again, then looked all the way around the house and also checked with my 4 neighbors, and none had received it. All weekend, still nothing. This delivery was supposed have occurred on a Friday. I went to the post office on Monday and asked to speak to the post master. She listened to me and then said a "Sub" had delivered my mail on Friday. Then I was told that their tracking system takes a photo of the house where the delivery was made. I asked to see the photo, because my house is 600' from my mailbox and not visible from there, but I wasn't allowed to see the photo. I was told that they would look into the matter and that I had to wait a week and then file a report, which I did. Well, it's been almost a year and I still don't have either an explanation of why my package wasn't delivered to me or my glue. Their attitude is "it was marked as delivered" and they could care less where.
I ended up driving almost 100 miles to get the bottle of glue that I needed in order to be able to complete the project on time. I haven't had this problem with either FedEx or UPS, although their new drivers have left packages at my garage, back porch, front porch, wood shop, and even the next door neighbors on occasion, but all were relatively easy for me to find.
Central North Carolina