I like to create my own 404 pages and in a Foundry project, I discovered that all the stacks are stripped out what the Htaccess file send it to the 404 page.
When a chose Voyager Pro for that page, the General tabs says that this Theme does not support banners. Is this something new for RW 8.1?
If you can use a theme you should be able to use stacks for your 404 page.
That said, Voyager Pro still support banners, nothing has changed there. Voyager Pro was designed specifically to take advantage of that new feature in RW when v7 was released. I worked with Nik on getting that feature added into that release. If you’re running into this error you’ll want to report it to Realmac.