I was trying to use the sequencer as a simple modulator of a param, but setting it to "one-shot" mode with a length of one step loops forever instead of playing only once.
The one-shot mode works if the length is anything greater than 1 step.
I think your use case ties in well with my feature request to allow the sequencer to work in more of a step programmer mode that move one step per key press. That would give you the ability to move through many steps of what you were trying to do with a single step. That mode would be perfect by setting up the length of the cycle as you did with a single step, or at a larger number to let it scroll though each time a gate is triggered by a keyboard press.