ModemManager eating all CPU

I regularly see the ModemManager process taking 100% (or nearly 100%) CPU in top, making the phone very hot and draining the battery. This happens even when the modem shouldn’t be doing anything (not making a phone call or exchanging SMS, and on WiFi). The only thing I can do in that case is to flip the kill switch and then turn it back on, but then I have to type the SIM PIN again, and reset the mobile internet if I need it.

Anyone has the same issue (and maybe a fix/workaround?) Or what can I do to troubleshoot this?