Trouble on photon chat

Our game uses photon chat system.

After connecting to some channels and subscribe,
does not run OnSubscribe / OnStatusUpdate on photon chat server.
And does not come any response at all. (Actually it occurs at some channels only, not all)

This trouble occurred from six hours before.(And still has continued.)
Only a few users remain at that channel but it does not go well, at all.
Have any troubles on photon chat servers?
Or I suppose subscriber's amount per channel of photon chat is unlimited.
It there any misunderstand for that?
Is there any limitation on it?

Our contract is 10000CCU, and it's was 1200 users when the trouble occurred first.

I'm looking forward to you reply as soon as possible.

Thank you.