Non-looping banner ad animation html exports are not stopping on last keyframe

The banner ads are non-looping and should end on the last keyframe. The HTML exports all animation to the end correctly and after the last keyframe they arbitrarily stop with a random set of layers.

Is something different in the lastest version of Animate? Do I need to set a stop for the last keframe? If so, how? 

Thanks!

(I cannot share example files.)