Sadly, the event of a lava spawn creating another doesn't trigger the Spawns Summoned Unit event, so something that's a bit more of a hack is needed to fix it (tested and working):
Trigger:
Lava Spawn Fix
Events
Unit - A unit enters (Playable map area)
Conditions
Or - Any (Conditions) are true
Conditions
(Unit-type of (Triggering unit)) Equal to Lava Spawn (Level 1)
(Unit-type of (Triggering unit)) Equal to Lava Spawn (Level 2)
(Unit-type of (Triggering unit)) Equal to Lava Spawn (Level 3)
Actions
Custom script: set bj_wantDestroyGroup = true
Unit Group - Pick every unit in (Units owned by (Owner of (Triggering unit)) of type (Unit-type of (Triggering unit))) and do (Actions)
Loop - Actions
Animation - Change (Picked unit)'s vertex coloring to (100.00%, 100.00%, 100.00%) with 0.00% transparency
Ghan has said he has fixed this. Monovertex please confirm this fix. This was only a problem with people that had signatures in the upper levels like not the special members but the respected members.