an issue regarding preview

so basically , i finished making my edit and i always clear up my memory and disk cache before i render as i would preview it all again and have clear storage in my ram for it if that makes sense. I use a macbook pro 2019 with 8 gb of ram and its worked perfectly, never an issue with the ram even if it is small. But as you can see the preview is now gray. All i did was clear up the memory and disk cache and now it wont perview, when i hit space bar for preview it does nothing and when i try to close AE it goes unresponsive so i have to force quit it. I went to other project files and they are working perfectly fine , i even make a new one and it was fine. On the new one i added this peoject file and ended up with the same issue. I was given no error ,no nothing ,just the problem first hand. Also the version i am running of AE is 17.5.1 and i use macos Big sur.

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