My save game references a variable which is of type MyStructure.
That structure needs the definition of actor A ( I got it a bit wrong up there ), to be complete.
Actor A references Actor B.
Actor B references my save game…
Well, in c++ this is easily solved with forward declarations.
In my opinion, when something can be solved that easily, the circular issue is not actually bad.
Yes, almost everyting in everyone’s projects are actors. But, they are children of actors. The same way a Pawn is an Actor with more stuff.
Your actors are also actors but with more stuff.
Take a look a this pic.
“Ref2SomeActor” is of type Actor, and because of that, like Tuerer said: " you don’t call any class-specific functions" because you just can’t, unless you cast, then you have access to any function you implemented in that BP.
Without the cast, you can only send interface messages or use any default functions that are available in every Actor, like “GetActorLocation”.
Yes, I get it - thanks 
Would be nice to find someone though ( maybe from Epic, or some real engine hacker ) who knows if it actually matters if you have symbiotic BPs…
I don’t want to spend weeks unpicking loads of code if it doesn’t matter.
Sorry, if my explanations doesn’t make much sense. I’m really bad in explain stuff extensively.
It’s a lot easier to explain in code.
It’s fine, I get it 
Unfortunately crashes with large size projects 
Contact the vendor, very responsive. They fixed a bug I found ( with a large project ).