Copy and paste screws up undo

since some months i have the following problem:
when i do a copy / paste in rhino (no matter if from another rhino instance or from within the same), i lose the possibility to undo. the command line just outputs “nothing to undo”. this is quite a pain, if one tries to get back to a file state before the paste action, which i need very often.
this is very annoying. anyone else encountered this? is this a known bug?
i am on rhino 5 SR11 64 bit

Hi Roberto - as far as I can see this works OK here - does it do this if you copy/paste something very simple, like a line?


hello pascal,
it happens with any kind of geometry, from a single point to large sets of polysurfaces. i cant remember if it happens always. today it happened repeatedly for several hours, thats why i posted it.
just tried it on my laptop at home. and it works as it should (rhino 5 SR12 64 bit, win7 64 pro)
any ideas, what could be the reason?