Hello,
Thank you for posting your question.
It seems the error doesn't like a field called 'At Customer Site' from the 'Resource' Table....and then it is referencing a table called 'Site Location'.
I am not aware of the field 'At Customer Site' from the 'Resource' Table, nor the 'Site Location' table.
Can you confirm if this is a base NAV field 'At Customer Site', and a base NAV Table 'Site Location'? They almost seem like a customization/modification your Partner has done. If so, you may want to check with them, as I'm not sure if anyone on this forum would know anything about that. Thank you and be safe :)
Bryan