How does the Cyclone Lock On ability prioritization work in Starcraft II?

How does the lock on ability work on auto cast? I notice a lot of the times that cyclones don't target buildings, but what about buildings that shoot back like spines or planetary fortresses? How does the lock on work when the cyclones engange in battle? Do they spread out the lock on maximally? Do cyclones never autocast on a unit that has already been locked on?

According to Liquipedia, lock-on auto-cast only targets units and combat buildings except larva and broodlings. Auto-cast also only targets units that are not locked on.

You can, of course, manually target buildings and units that are already locked on.