Magically disappearing plants

Here's the situation: In a volcano level, a tier 1 plant is covered by an Umbrella Leaf, protecting it from Saganaki Blasts. Now that tier 1 plant is targeted by the Saganaki blast. If I timed it where the Sanganaki Blast, Umbrella Leaf's ability, and merging of the tier 1 plant  into tier 2 at the same time, the supposed to be tier 2 plant just disappears. This is what I experienced while playing.