Yes, Vegas is documented to have limitations when importing numerous
Quicktime files on the timeline at once for most users, i’ve never come
across that limitation in my personal workflow however.
So the best advice i would give you is to simply work and render in increments/segments, then drop them back on the timeline for joining and
final render.
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