Changing between real kits and fake kits

Hi,
I have a career with Liverpool and downloaded a couple of SS kit packs and 3d kit packs and in the premiere league they all work fine. However I have experienced that when a play league cup/fa cup or another domestic cup against other teams from PL and Championship they kits doesn't work and the default kits are used.

Can anyone give an explanation to this, or help me fix it?

You'll either need to use the FM18 editor and remove any kits that have a competition set, (FA Cup, Champions League, Europa League etc.), or if you have it, the In-Game editor, and do the same. In-Game editor wouldn't need a fresh save, the FM18 editor would.

Thank you