Open the UMP portal go to the control panel, users and organizations and make sure you don't have user with special character.
Below are the samples that you must change.
User like "produção", remove and add a user like "producao" without the special character.
Another sample as "informação" and you should change to "informacao"
Remove any special character that is related to the UIM users on the UMP portal.
This will resolved yours issue and you will see the final synchronization message as below:
[UserSynchronizationThread, cabi] Finished synchronizing users between UIM and CABI