> You say it should be one or the other, so which would your actions apply to?
It would apply to the instances that were picked as part of the condition that returned true. In other words, any instance that returns true for an OR condition would be picked.
I find it's better not to think of it as returning true or false, but instead returning a number of picked instances. If you have a condition 'sprite is X' as part of an OR block, and there are no 'sprite is X' I think of it as 0 instances matched, not that the condition returned false and therefore should be ignored and all instances are still open to being picked.