I just got off the phone with a "Senior" support specialist. I too have the NPE-240A, and this is what was explained to me.
1. When its just the water heater there is a 30 minute/9 degree re-circulation default set up
2. Connecting a Hot Button or a Navilink controller to the tankless water heater disables this default because it is assumed that when you hook a Hot Button up you will only want it recirculating when you engage it to do so manually, and when you hook up a NaviLink that you will want to have schedules set up. If you have a hot button and a Navilink hooked up you get the option of one or the other in the app. not both.
3. This means that when the schedule is disabled it will NOT heat/recirculate.
4. It means that when outside of the schedule parameters it will NOT heat/recirculate.
I set my schedule for 7AM when I wake up to 10PM when Everyone would no longer take showers. From what I was told this means it will not run/recirculate overnight from 10:01PM to 6:59AM because of this schedule.
5. So having found this out, it would seem that the only way to engage a "hot button workaround" would be to enable the schedule...have it figure out/sense the reservoir tank is cold and begin heating the reservoir tank and therefore initiating a re-circulation. There is not a workaround if you have the schedule enabled; disabling it does not initiate a re-circulation.