Hi Yubi,
I tried saving TnC in your ED backend and it seems to be working fine(https://www.screencast.com/t/t5d2LcFmtN).
Am I missing something here perhaps?

Hi,

It can be saved, yes. But the problem is after a while, it will go empty and i dont know which settings did i save to make this.

I believe if i do some other settings in Easydiscuss backend, the T&C section becomes empty. Please advise.

Hey Yubi,
I see. Unfortunately, since we do not know how to replicate this exactly, we would not be able to investigate this. I would suggest that you keep an eye out on the T&C section for every change that you make in ED backend. Once you find a definite setting that causes the issue, let us know so we can investigate this.