EAM Send Tags Fails with Exception "Cannot invoke "String.toUpperCase()" because "value" is null"

EAM send tags task is failing with an error trying to send some standard tag UDTs we use from central development server to a specific production server (same UDTs successfully sent to other production servers):

Tag JSON import operation failed [Standard]types/: Error_Exception("Cannot invoke "String.toUpperCase()" because "value" is null")

Any idea what could cause this?

Ignition 8.1.41

Update: Editing the send tags task that was failing, going through all the edit steps to finish and then rerunning the task was successful. I didn't change anything, but it seems something must have been corrupted in the task config that was corrected by going through all the edit steps.