If the project you’re working with is purely blueprints can you explain where the code in the first post is coming from? You mention trying to downgrade from 4.10 to 4.9, did this problem first start right after upgrading to 4.10? If possible could you send me a copy of the project that isn’t opening? If you’re able to upload it somewhere like Dropbox you can post the download link here or send me a PM on the forums with the download link for privacy.