I hate to list them together, but the cause for all of them is likely the same. Notably, the following enemy editor flags seem to not work under any circumstance:
Spawned by "Corner Traps" Enemy Flag
Spawned by "Middle Traps" Enemy Flag
Spawned by "LR Trap" Combo Type
Spawned by "UD Trap" Combo Type
The other three work fine, but these four seem absolutely set in refusing to let me generate enemies through them. The names are fairly ambiguous and match poorly with the actual enemy flag and combo type names, and I'm assuming that LR Trap and UD Trap refer to the continuous trap combo types (since the horizontal and vertical enemy editor flags impact to the line of sight ones). Again, I'm not sure if I'm running into an actual bug or an unimplemented feature, but either way, buttons that say they do something and then don't do it are not good.