Things have been partially fixed but are still an issue. I can now attach the certificates to reservations but apparently not for category 7 hotels at the off-peak rate of 50k points. And that is what I was trying to do. It appears I am not the only one with this problem. Duckyfly has posted the same issue here-
https://www.flyertalk.com/forum/marr...thread-50.html
I have been messaging Bonvoy Lurker but so far no solution.