I don't get it why but there are no chat messages.
I have set:
Disable chat countdown notifications": false
And I use custom reference points like every 10 minutes from 60 minutes on and have set:
"Use custom countdown reference points": true
The UI works but no chat messages at all.
Only when I restart the plugin I get in instant message of how much time is left but not at the custom reference points.

Is this because I use Better Chat?

Because you have the chat messages disabled I would assume:

Disable chat countdown notifications": false​

No. I have Disable chat countdown notifications": false
And this should mean that they are "not" disabled, right?
Anyway, I tried the opposite and set this to true. No change.

Buuuut I just noticed that the chat countdown starts 1 minute before restart and counts the seconds. (Disable chat countdown notifications": false again of course!)

But it should start at 60 minutes and the last one should be at 1 minute. All these seconds don't come from my reference points.