The way this works (simplified a bit) is the OPERATING carrier reports to the AWARD Program carrier the flight was taken and needed info to determine earnings. The OPERATING carrier "pays" AWARD Program carrier for the credits earn. It reality, for a period of time the flow of these cresits between the two carriers are tracked and then some payment is made dependent on the net balance.

So UA generally will not credit a partner flight without the partner acknowledging credit is due and they agree they are responsible for the credit to be posted. This sounds a bit more awkward then it probably is in reality.

When one requests a missing credit, UA reaches out to the partner to validate the missing credit. UA generally will not proceed without the partner's validation.

The factor UA was not the ticketing carrier makes this more difficult as UA has no visibility on your flight activities and is 100% dependent on LX/LH reporting. Things such as fare class that determines earnings are invisible to UA