I cannot save, import, export,render my projects

Hi,

I am using Adobe after effects CC 2020.

MacBook pro 16 inch late 2019.

MacOS Big Sur

When I open After Effects everything works fine. I can import, save or render. But after adding some animation, let's say after 5-10 minutes I can't access my storage via AE. I mean I can't import, save or render. When I try to render it freezes but I can move my cursor also click some options, but I can't quit or save before quit. When I try to save it shows nothing, no dialogue box. Even if I try to import nothing happens. No dialogue box opens up. Even the auto save option doesn't work. I think there's no access to the storage. I have already lost my 5 hours of work and this is 3rd time I'm facing this problem. please help me.