T657 - Mystery changes on NOA

Does anyone have experience with unexplained changes from T1 as submitted to NOA on initial (automated) assessment?

I have a file with the T657 populated via AFR (and with CNIL balances etc carefully checked by hand) yet the the automated NOA revised the CGD to a lower amount as “the maximum permitted” without any details or further explanation. And of course, the T657 is not included on the T1 details provided by Represent A Client, plus there is no hope of anyone to call given the current environment.

Any comments from others with a similar experience would be appreciated.