It's not generally the case that multiple trigger events all need to be "true" before a rule will trigger; trigger events are just events, which are just an instant in time and cannot be "true" or "false" per se. (This gets more complicated with the latest Rule 5.1 update that adds "sticky triggers," which check that the state resulting from such an event remains true for a certain period of time.) Regardless, any trigger matching will cause the rule actions to run.
However, you have a single "all" trigger here. This is also a more nuanced approach that should wait until all the devices (in that particular trigger) reach the desired state before truly triggering. See the new "all devices for triggers" option in Rule 5.1, as described here: Sticky Triggers and Other New Rule 5.1 Features
So, if that's what you're seeing, I'd say it's a bug. @bravenel would be the one to look into this. You'll probably get farther with log entries that verify the issue (I haven't tried to replicate), but perhaps there is a problem he can see offhand...
