Jumping spell effects: Hornets Swarm's case

[Rodmar18]

Hello, it looks like Hornets Swarm''s effect can't jump over a unit if it can't affect this unit. How else to explain the discrepancies on the screenshots?

Do you consider this as being a "bug", or rather resulting from an engine limitation?

 

[Zaskow]

This is feature of this targeter. It must have 1 targetable unit to work.

 

[Rodmar18]

Your explanation certainly explains screenshot "hornet3", where first target is an invalid target.

I would have thought that screenshot "hornet1" is the normal behaviour, having the swarm jumping up to 4 times, invalid targets included (and not affecting them).
But in this case, why on screenshot "hornet2" isn't the invalid target jumped over and the Unicorn Riders left non affected?
Moreover, why on screenshot "hornet4", do we have 7 tooltips, whereas I would expect 5 (first target + 4 jumps) at most?