It is impossible to attack Wallachia as Poland or Commonwealth

[FrozenGrenadier]

In my last game which i was playing as Poland, Hungary attacked Wallachia and annexed him before Ottomans and after some years i checked moldovias claims he has claim on Muntenia which was Hungary's core province, after some heavy fighting on Hungary Wallachian rebels uprise and Hungary had no army to stop them so Wallachia returned and i was like yes it is my chance and i checked moldovias claims again ta da his claim is no more so i just move on dont think about it too much
after some more years i formed commonwealth and attacked and vassalize Hungary before i attack i checked that he still has cores on wallachia but as soon as i vassalize and peace with hungary his cores just disappeared
why?
is it a bug or something or developers done this on purpose to prevent commonwealth from intervening into wallachia?

 

[AurochsAway]

Cores disappear after a certain time. There is no reason the Commonwealth can't get into Wallachia.

 

[Mztr44]

Your post is a little difficult to follow, but if I understand correctly, what happens is that when nationalist rebels enforce demands, it wipes the cores from the occupying nation. So it's just working as designed.