Update: in next day they said "It is global restriction we try to solve it as quickly as possible , we are very sorry to keep you wait but please be patient."
This was exactly my thoughts as I read through your post. If Betnomi wants you to complete KYC, why disable the button leading to KYC?
If you upload your documents multiple times and every time they get rejected, then the service may disable this option for you to avoid any attempt to abuse it.
However, if the service rejects your documents and don't let you pass their kyc verification, they must explain why they did so and explain what you are supposed to do to fix the problem. Rejecting your documents just like that without no explanation is a shady behavior. Just my opinion, though!