Hi. http://johnstonnow.com/events/2017-03/ took a very long time to load, which is not good–typically a sign there are other issues with your site.
Anyway, to your reported issue, I looked at the .ics file you provided and it actually includes the events furthest in the future (really just the recurring events 24 months out in January 2019).
I do see that your site’s .ics output is the same for all months, and I was able to reproduce this on my local testing site.
I’ll mark this ticket as Pending Fix, which means this thread should receive a reply once the applicable fix has been released. I cannot guarantee when it will be fixed as it’s in the development team’s hands now. They need to assign it, code it, test it, and schedule it for release.
I apologize for this issue and appreciate your understanding and patience.