When you drop the 4K footage on the timeline and trying to pan and zoom with it, What actually happen?
I work with 4k footage on a regular basis and have no issues nor issues like that none at all.
I am left wondering if that particular 4k footage you have, uses a codec format that does not sit well with Vegas!
Steve Rhoden (Cow Leader)
Film Maker & VFX Artist.
Owner of Filmex Creative Media.
Samples of my Work and Company can be seen here:
https://www.facebook.com/FilmexCreativeMedia