We've identified this issue as a bug and a fix will be released in a future Mosaic update. We'll share more details, including expected timelines as soon as they're available.
In the meantime, you can use this workaround. This action updates the group name and should temporarily fix the issue:
Log into Mosaic.
Click Organisation.
Select Find organisation and search for the one you need.
Click on the organisation from the results.
On the Organisation summary scree click Organisation details.
Select Basic details.
On the Amend organisation screen just click Save you don’t need to change anything.