Sorry about that. We have discovered this issue was introduced in 14.0.8 Beta build 25 and should be fixed with the next build.
Glad it's not just me. I also tried downgrading to past builds and the application just won't open. I get the little dot under the Pr logo in my dock, but nothing happens.
I thought I was the only one experiencing issue with today's beta build. I tried every trick I know and it still would be stuck on a spinning beach ball.
We just pushed 14.8 Beta build 026 to Creative Cloud, which should address this issue.
In case anyone is still having issues opening Premiere Pro Beta (when I tried, nothing opened after attempting to open a project), go to the Beta menu and enable any features you had previously enabled. That got my projects opening right away. PHEW!