I received a call that the elevator is shutting down twice a night (only at night) at 9:30 and 11ish. Door opens to call on ground floor. Push call button to upper floors and nothing happens (call lights up). If someone walks up and calls up and calls it it will go up. All the while blinking the ground floor button, and first floor button. After about 20 minutes it sorts itself out and begins working.

Any ideas where to start on this weird happenstance?

What if any errors are logged?
Same time every night? Maybe something to do with RCY (viscosity control). Disable it and see.
Another idea might be a zoned parking issue. I can’t remember how this was performed it was so long ago, but we told this unit to not park in the lowest zone and that took care of the issue. It always took a crap overnight when it ended up parking at the bottom landing.

That sounds plausible. Thank you for the help. I will have the tech take a look at both of these items.