All of the content is either base source content or included with the map. I test every upload to make sure the included content is working, so this is likely related to an addon you have installed.

Try disabling all of your other addons and let me know if the problem continues.

OK. I'll uninstall some addons then.

I disabled Luammer and the doors are visible again.

I wonder why Luammer makes the doors disappear. I can't think of anything I could do on the map to prevent that from happening. It might be a good idea to let the Luammer dev know that it's causing this.