Minecraft banner limited?

Games 1.13 vanilla on a server (Nitrado)

Whenever I try to reconstruct various banner templates from the internet then I can't do more than 6 patterns on a banner. If I try it anyway I will not get a banner back, or the recipe will not work (yes I checked, it should work). Why is that and can I somehow pack more than 6 patterns on a banner without commands?

That you can have only a limited number of patterns is normal.

The number of patterns is limited to 6.

Make a command block and paste the command displayed on the banner page. So you get more complex banners.