The User Activity Log shows an error: Unable to parse: ERROR: Unexpected token in group expression: Owner at index 27. What is the root cause of this issue?
Offline Validation rules do not support the Owner field. The Owner Field is used to support the application global variable.
Users attempting to create Cross-Object Owner formulas to retrieve information on objects that can have owners of different object types receive this error.
Do not use the Owner field in the validation rule.
Vault Help Documentation: Offline Validation Rules