This is now fixed in Mosaic version 22.2.4.0
This is due to the Unrestrict button on the Person restrictions screen ending all 'Restrict to' access records.
We're aiming to release some changes in Mosaic 22.2.4.0, from this version the following will happen when clicking the Unrestrict button:
All the restrict to workers, roles and organisations will be deleted from the restrictions (where currently they are ended).
Any restrict from workers will remain as is.
Audit of the restrictions will be retained in the tables.
No one will be restricted from the case other than any workers 'restricted from' that case.
In the meantime, the workaround is to manually delete the Organisation restriction and retry assigning the incoming work.