Actually, you should probably avoid github, unless you’re willing to release your project under opensource license. You’re releasing it under opensource license, if you’re not paying money to github. Opensource means that anybody is able to make copy of your project and derivatives from it.
The issue you described could happen if you put your project into google drive folder. Google drive exists in order to murder your data under guise of working as cloud storage. It will lock files while uploading them, that can crash the editor. So, google drive generally should be closed while you work in unreal editor.
You can find who keeps file open using sysinternals process explorer and some other tools.
In case of process explorer you do that by going into Find->Find file handle or DLL and typing locked file name.