Why don't my classes show more than about 3 months ahead?
The calendar shows about 3 months ahead - later recurring classes appear as their dates approach.
Octiv's calendar displays classes up to about 3 months in advance. This is a display window - not a limit on how far ahead you can schedule.
If you set a recurring series to run further out - for example all the way to Christmas - the later classes are still saved and will run. They simply don't appear on the calendar yet, and become visible automatically as their dates move into the ~3-month window.
So if you scheduled a series months ahead and it stops showing partway - for example, nothing appears after a date a few months from now - nothing is wrong. Your end date is fine, and the later classes will show up on their own as time passes. You don't need to re-create or re-edit the series, and you haven't lost anything.
Related: How do I add a once-off or recurring class? and What's the difference between Recurring Events and Recurring Bookings?