Syed, Mendix 8.0.0 Beta 2 (build 52780) is now available for download from https://appstore.home.mendix.com/link/modelers/
Mendix Studio Pro 8 is still in Beta. I’d expect such issues. I would open a support ticket if I was in your position (if this is critical); otherwise, if your project is still fresh then just start over.
If you’re working on something critical I would suggest working on a stable Mnedix Studio Pro version.