See attached test.

It consists of a SequentialTransition whose contents include:
1. a sub-SequentialTransition whose duration setting was not explicitly set (will refer to this from now on as "tr1")
2. followed by another Transition (fade) with an explicit duration setting.

This is an easy mistake to make and, in fact, the example in the apidoc does not set the duration for the SequentialTransition explicitly.
It would be expected that either SequentialTransition would get created with the correct duration = sum of the duration of its sub-components, or that each element of the sequence would be executed (and verified as finished) before the next is started.

However, it seems the default duration is set to 0. When executed, the run-time believes the duration value of 0 and starts the next transition in sequence immediately. The end result is the animation is out of sequence.

Workaround would be to explicitly set SequentialTransition.duration.