I have recently been experiencing more situations where I have a two leg UA journey and one leg credits immediately upon landing and the other four days later. Sometimes it is the first leg and sometimes the second leg.

I keep a screenshot of the BP for the missing leg until it credits.

I actually feel much empathy for the IT folks at UA because as best I understand this information is on different systems so sometimes they talk and sometimes they must be taking a nap. You can tell I do not work in IT but know enough to feel their pain.

Now Lyft miles are practically instantaneous, and I have some LH flights at the end of the month and will keep the BPs until credited.

Eventually it all catches up.