I wanted to export a project from Vegas Pro to Premiere CC 2019 but Premiere crashes when I try to open the file. I found out that an .aaf file can make the magic trick but messes up the soundtracks, every stereo is read as mono and Premire creates lots of new soundtracks for no reason. I have to change the sequence' resolution, too because it's read incorrectly.
I have been waiting for this problem to be solved for a long time. Exporting Vegas projects in .prproj format does not work in new Adobe Premiere or After effects. No explanation given by Vegas pro Team, and no assurance regarding possibilities of a solution in future versions.
The best way (for me) to import or export between Vegas and Premiere is to use .XML files (Final Cut 7/DaVinci Resolve). You won't get your effects with this methode. But at least you get Premiere to work with Vegas Pro and vice versa.