Underused Housing Tax - Error Line 547

Trying to e-file an UHT for a corporation with multiple properties and received an error regarding line 547 - common dates. I have stated that the unit was occupied by a non arms length person for 365 days and I have not selected any other options regarding occupancy. What are they looking to go into line 547? I feel that should be 0 but its getting rejected with that value.

CRA appears to want a value at line 547 even though the specification says that field is optional. Try putting 1 on line 547 and see if that will go through.