I got the Christmas update to my MX last night (2023.44.30.4) and now my Intermittent wipers are working just fine on both slow and fast intermittent settings. To be clear, they are working for my first drive after the update. I still need to see them work more than once to be sure they are fixed.
It looks like the fix I received is functioning more like regular intermittent wipers using a time-based control:
Slow Intermittent speed = 1 wipe per-5second interval with or without rain.
Fast Intermittent speed = 1 wipe per-2.5second interval with or without rain.
Not running auto-wipe mode. maybe that will change them to being something other than time-based intermittent wiping.
So nothing fancy but they work. I'm happy with simple and reliable.