Nuendo 13 convert stereo to mono tracks issue

When I have multiple tracks that I want to convert from stereo to mono, the process sometimes stops working (usually after about 3 or 4 tracks)
I have the command under a shortkey.,
I need to quit en restart nuendo for it to work again.
Very strange and seems a bug… (In Nuendo 12 there never was a problem.) does anyone else have the same issue and/or solution?
Would be nice! :slight_smile: