put a test in for a start to evaluate platform and mode, and see what you get. Has the remote hoster changed platforms for their FMS12?
Unfortunately that isn't a straightforward as it sounds. To ensure that a simple Get Host Application Version test is evaluated in the remote hosted database and not in the customer's client, I have tried to run it as a script in the remote database, called from the customer's database. That fails for the same reason that calling the delete record script fails - error 3 again.
Maybe I would try a simple new table and schedule to run a simple script to delete record, and log to a text field the step through result. If it is only a couple of steps ( delete) then this would establish delete is capable of running, and then it is maybe a privilege issue... i.e. building block start form absolute basic and build up; when all else is not being co-operative. Deconstruction and recreation, rebuild the process step by step to see where failure point is.