Anyone have problems with bosses not spawning?

I have a mission with 5 non-required bosses with no spawn conditions. On one map I had, none of them spawned. On the current map, I think only 2 of them spawned. 3 of them have ambushes attached to them. If you want to take a look, I don't remember the arc, but just search for Bubbawheat, and it's my lowbie logic puzzle.

I've just run into some problems like this on the outdoor Malta/Warburg map (basically a small "docks" map.

My mission has 5 bosses, who spawn in sequence.

The first time I tried it, I had two bosses spawn at mission start, one of whose defeat would trigger another two, then one of whom would trigger the final boss. In this circumstance, the first two spawned properly, but no more appeared.

The second go, I tried just making them purely sequential, one and only one at a time. This time, the boss didn't spawn at all.

Are there problems with this particular map, perhaps? It is awfully small, which is perfect for my needs, but I can see how it might cause problems the MA system.