I also had a very similar issue to this - I had several log entries say the asset is to new, but when I navigated to the folder in the editor - The folder was empty.
When I went to the same folder in windows browser it had the UE assets in them. I wasn’t using any of these assets in the project (or could have replaced them), so I just deleted the windows folder directly (as it wasn’t deleting via the editor). I would exercise caution doing this, make sure you have a backup of the project and also have ran the fix up redirectors from the top level content folder.
After I deleted these folders though the build worked.