Membership 2 Pro erroneously sending automated emails multiple times

I am using Membership 2 Pro on my website. I updated the plugin a few days ago and automated emails are now being sent a month after a membership subscription has expired.

Three members were emailed correctly at 00:01 on 22 December.

Then a fourth member was emailed at 6:01 on 23 December, then again at 12:01, then again at 18:02, then again at 00:01 today. It looks like she is going to be emailed at 6 hourly intervals, possibly without end.

I have disabled this automated message and sent the member an apology.

I recall this was a problem when I first installed Membership 2 Pro - see:

I had to disable the reminder emails previously, pending it being solved in an update. I'm not sure why the reminders suddenly started again after I updated, but I've had to disable them again as I cannot have members being emailed repeatedly like this.

Is there anything being done to address this problem? It is a useful feature, but not with this bug.