I just made a new group, and after doing that, I restarted the HA.
That gave me a lot of problems, and a complete crash, also the hassio had problems, and I couldn’t connect to it via SSH.
After a lot of rebooting, I got hold of the hassio, and removed the group again, and everything is back to normal.
The group consisted of only one other group, I have groups of groups already, and they work, but there are more than one group in them.