@Mike Brown If you are getting 404 error with Get file content using path action then that means that your Path
variable is not correct or when you are dynamically creating it may be missing /
in your path or the file name/file path will be incomplete/incorrect.
Example:
/Lists/ContentTypeSyncLog/myfile.text
I will suggest you to navigate to the run history of your logic app and verify what File Path
string is dynamically built and verify the same with your SharePoint file path if it is correct.
Feel free to get back to me if you need any assistance.