Disclaimer for my comment:
I’ve only tested this on Windows. Can you confirm that, in the issue you are experiencing, the Unreal version consistently shows the little yellow exclamation mark next to the installed plugins button? And when you open Epic Games, does it prompt the warning below, and pressing “fix now” does not resolve the error?
If so, the following worked for me. I hope this helps. And to be safe, quit Unreal and end all Epic Games-related tasks in Task Manager.
And I am not a tech expert; this method just works for me, so it might not be a permanent solution.
Step 1:
I found the solution: go to your Unreal Engine installation, usually in one of your disk’s Program Files folders. Now go to “Epic Games” → “Launcher” → “Engine” → “Binary” → “Win64”.
Now, find “UnrealVersionSelector.exe”, usually a blue Unreal icon, and copy that(But keep this file where it is).
Step 2:
Now go back to the “Epic Games” Folder you entered this from, and pick the folder name with the Unreal version name; in this case, it is “UE_5.7” for me.
Now, go to “Engine” → “Binaries” → “win64” inside the “UE_Version” folder, paste “UnrealVersionSelector.exe” in, and run the .exe(with admin perms just in case.)
Step 3:
Now boot up Unreal again; it should work fine.
Note:
If the “UnrealVersionSelector.exe” file is in the “UE_Version” folder but not in the “Launcher” folder, paste it there; just make sure both folders contain the file. (And run the .exe in the place where you pasted it.)
If this does not work, it is outside my troubleshooting experience; please criticize if my solution is flawed or poses future risks.