Make/Break Post Process Settings nodes are the weirdest nodes in the engine right now. You need to disable the bools for every property(especially Blendables) and enable only those you need if you want to work with them easily.
https://.unrealengine.com/showthread.php?5938-PostProccessSettings-node-is-too-****-long-!&p=45395&viewfull=1#post45395
Copy those and paste(ctrl + V) in the blueprint, and you’ll have post process settings nodes with every property disabled. Then enable only the ones you need and you shouldnt get any errors.