Alembic file plays back much too quickly

I have a 7 second alembic file exported from Houdini.
When I try and play back and or render in Sequencer this fil plays back much too quickly in about a second.

What is going on?
I notice that on import you can choose ‘Time Step’ instead of by Frame.
Checked the documentation but not much help.
What value should I try for Time Step?