I've only ever tried to use a Visa credit card in Russia, but never had any issues anywhere. I was in Russia as recently as last November without any problems.
Debit card-wise, I've not been able to use my Chase Debit card at Sberbank ATM's for a few years now (always displaying a declined transaction message, even though I have no fraud declinations or anything on my bank's end), but it seemed to work fine everywhere else, including VTB, which was also a target of various sanctions... so, I'm not sure what conclusion to draw in this case, exactly.