I’m not sure what is the cause. It was set to automatic from start.
At first the time was in sync, but after some hours of use there was a big time difference.
Don’t know if it could be that some of the ntp servers is giving wrong time ¿? or if it’s something else.
I found this line in my messages: Jul 15 18:54:09 ns7b1 chronyd[16079]: Can't synchronise: no majority
Apart from that, sometimes chronyd seems “slow” to adjust time (seen on a vm which I susped often).
I use: chronyc -a makestep
to force a clock adjustment.
I installed NS 7b1 on a dedicated server and there is no chrony issues (except that if you want to see the real time on Dashboard, you must refresh the page, or go to another menu and switch back; can you do something with this?).
I suppose that, as @filippo_carletti said, it’s happen only on VM.
I checked again on VM and the issue is present.
The curious thing is that with NS 6.8 on VM, no chrony issue (if I remember well; I will check).