Can't run Xcode 11.5 on Catalina Beta

I still have Xcode 11.0 on my alternate hard drive (SSD) with a Catalina beta installed. I tried installing 11.5, but the Mac App Store refused to do it. I found the general developer downloads site, and grabbed it from there. But the app icon has a white barred-circle around it and won't run. I think I have the latest beta on the hard drive ("10.15 Beta (19A582a)"). I'm also going to try Xcode 12.0 beta 2.