Just tested my 9.6 for some more time. No issues. So I think something broke when the code was updated.

btw one correction
-u wallet_id.PAYMENT_ID.(rig_number)
Right, never mind, you got my idea

btw how did you know that pool is repsponding to shares that miner did not send?
I not made a deep investigation on log, Claymore says this in PM to me.

I have sent Claymore my log of whole 6 hours of 9.7. So lets see what happens
Yes, let try to be patient a little bit, I try to be helpful for investigation

EDIT:
I think that something wrong with option (dot rig number) because have few rigs, on the same wallet/walletID, and if the pool not receive correct rig number, probably not communicate the right way with my rigs.
I think other people that have an issues, also with more than one rigs, but may be I am wrong