Don't know if this is a bug or i simply just miss something

[Acno_Cero]

So like i wrote in the title i did find something that feels odd to me. I did use a save game of Pokemon Sword for this. And on that i did check the Encounter Database for Zygard. Specificly on 2 of the Event distributed once.

The first one was the Shiny one from Sun. I was able to change it into all of the forms it has, meaning 50%, 50-C, 10% and 10%-C without having any problems. But now when i try to do the same with a non Shiny on the same Save File i got into some problems. Specificly the non shiny i used was the Event one available for all of the Gen 6 games. It has "XYZ" as OT and "05026" as TID.

For the Normal 50% Form nothing was wrong. But when i did try to change it's form into the 10%, 10%-C or 50%-C than it says that it is not legal because of the ribbons it owns? I mean the 50% one has the exact same ribbon but nothing is wrong.

As far as I see it's just the gen 6 ribbons it has a problem with but i don't understand it since it has gen 6 as origin game, Omega ruby to be specific. So as far as I know I can go with any Zygard to Route 16 and reconstruct it. That's why it let me change the Shiny one in all of its forms. But should the same not apply to a non Shiny Zygard? I mean technically that would be a gen 6 Zygard traded up to gen 7 and than going with it to Route 16 and also reconstruct it.

Oh also i just did try if i remove the Ribbons that it says should be removed and than it says they are legal whats confusing me even more.

So a Gen 6 Zygard with Ribbons from gen 6 is illegal as a 10%, 10%-C or 50%-C but without the Ribbons it's legal? 

Pls if that's not a bug could someone pls explain what iam missing.

Also sorry if that the wrong spot to ask for and thanks in advance :)