Yobit finally gave an update of the situation today. It's on the bitcointalk thread.
I don't know if these explanations are honest, as the FRN wallet is working smooth. But better than nothing.
Richx and Dem wallets fixed, resync in progress.
GSY and CBX wallets are very unstable, they crash every 70-90 secs. We are trying special scripts for it now, resync in progress.
We have 600+ wallets now, some of them stuck every 3-5 days because of another forks in network, some just crashing every 70-110 secs.
Sorry for delay with wallet fix, we are developing a new system for faster repair (/restarting in auto-mode), intelligence and inspection.