In Kopano - as in any editor - there is a function that can make accidentally deleted text visible again. Either via a button above the email or with[ctrl]+Z

The button is displayed actively and I can press it, but nothing is undone. Do I have to activate it somewhere (shortcuts are all activated) or can I deactivate it somewhere by mistake?

But this only happens on one computer. the others can use this function without any problems.

All Win10/64-bit 1803