REX maintenance cycle problem

Since mid March ( have only used by 2014 i3 for short trips (COVID-19). Now the REX says it wants to do a maintenance cycle because of length of time since it was used. The maintenance cycle will only run when the battery is below 75% so I have to go for a longer drive in the hope of running the maintenance cycle. THe maintenance cycle has run before but now when the REX starts up to do a maintenance cycle it runs for maybe 20 seconds and then shuts down. This repeats several times and then it states "unable to complete maintenance cycle". Today when I was still trying to get it to complete a maintenance cycle it stated after three or four attempts "unable to complete maintenance cycle. Vehicle can be used only in electric mode." Is it likely to be worthwhile to try to get the REX to run the maintenance cycle a few more times or is this a dealer problem?
Thanks for any advice.

Any ignition engine likes to be run periodically. Moisture can find its way into things and create some problems that regular running and the heat will drive out.

You might try to force the emissions test run. The same prerequisite of less than 75% is required. Probably get the same result.

A shop that can read the BMW specific codes from the OBD-II port might help isolate where the problem is. Some places with do that for free.

It could be as simple as a bad fuel pump relay, or something more serious.