Calendar not syncing between devices after 2 years

Hi I use OneCalendar to see multiple calendars at once in yearly view. However I noticed that events after 2 years are not syncing from my mobile to my tablet or my Windows app. Is this something that can be fixed please? For example I added an event on my android phone for October 2026 but this is not syncing onto my laptop or tablet. I've tried updating all the apps but this does not make a difference. I purchased the premium version too hoping that would fix the problem but it did not unfortunately. I appreciate your help. Thank you, Marcela