first of all, thank you for the fast answer. In my case the only solution what was working out, was a new Installation of Lightroom. I do use Acronis True Image for my Computers, so it didn't take Long, but it had to be done, after i even tried the live help. But thanks again for pointing out a solution and the time used for that.
Hi, i had the issue that all of the external editors even PS are grayed out.
I figured out, that the external raid becomes unmounted. I only had a smart preview in Lightroom.
After reconecting the thunderbolt cable the external HDD becomes visible as the menu of the external editors becomes clickable again. (CMD+E on a mac) was working again.