Copy and paste audio events doesn't work properly


Copy and paste on my Nuendo suddenly doesn’t work properly.
When I paste audio clips, it create new audio tracks and put the clips individually in the new tracks, not in a selected track.
And also, clip gain and direct offline process which the copied clips have are totally cleared!
That is very annoying…
The strange thing is, copy and paste sometimes works properly.
But most of times, doesn’t work.

Also, when I paste audio clips, audio import option dialog shows up if Open Options Dialog is active in Preferences-Editing-Audio-On Import Audio Files.
This means, pasting audio clips works as audio import?

I tried deleting preference folder and uninstall the program.
But, the problem is still here.

Does anyone know how to fix the problem?

My Nuendo’s version is 11.0.41 on Windows10.

Thank you,