Thanks for the details.
Presumably you’re using the latest versions of both Nuendo and RX7. There are ongoing bug fixes.
That seems to say it all. Some users here have had nothing but problems with the Nuendo/RX7 combination while others report trouble free use. Of course, you should not be seeing the waveform errors and clearly this is a bug of some kind. (You shouldn’t need to make the editing permanent in order to see the waveofrms). Where that bug comes from is another matter. There are known issues with RX7 and there have been very specific workflow recommendations elsewhere on this forum to avoid problems. For example, your issue may be linked to the use of ‘auto apply’ in DOP. See Fredo’s post here:
See also: