PU overlord not called into war

[TeutonicTortoise]

I'm in an Italy game where Portugal is a junior under Castile (I took aragon so no spain). Trying to form Roman Empire into WC so been attacking them after every truce but this time im declaring on portugal for Moroccos Cores but in the DOW screen Castile came up as a generally call in like an ally rather then the box being auto ticked for co-beligerant. It also showed a green tick for them joining anyway so wasnt bothered but after starting the war theres no Castile in the war.

Anyone any ideas? Feel like I'm missing something since its I've never heard of something like this before and attacking juniors in PUs is done all over Europe, like done against Lith, Hungary or Aragon so if it was a bug someone else would have experienced it and reported it

 

[TeutonicTortoise]

I just declared war on the overlord to see what that does and that has made all my vassals declare peace with the allies of the overlord that were called into the first war (Kongo) and Kongo simiarly did the same with me then went on to join my second war against the overlord

 

[Piotrzeci]

I played as Russia and declared a bit tricky war on Lithuania and then after a bit realized Poland wasn't in it. So yeah, it happened to me once.

 

[Astalic]

Had something similar attacking lithuania with oirat, poland allys joined but not poland. Just lithuania and poland allys.
Was a way more easy war. But i was greedy and got coalitioned by poland right after (a war where they lost their honor, manpower and monney. And i lost my time).

 

[Travis_Bickle]

I did this with the Mughals as Portugal ended up having Goa, they ere under a PU with Spain and Spain didn't join. It might be because the game considered it a colony or overseas territory.