Your events may not be syncing because of an iOS setting, which causes "Past events not showing."
Please see here.
If your events don't come back after changing that setting, they may have been removed from iOS itself.
Please check the steps in the next section, "All my events are gone (not showing)," especially "Try restoring from iCloud."
First, a bit of background: like most calendar apps, this app only displays and adds events that are stored in iOS.
If events disappear from iOS because of an iOS issue, this app can't load them either.
With that in mind, could you please check the following?
If access isn't set to Full Access, this app can't read your iOS events.
Even if it already is, switching it to "None" once and then back to "Full Access" may get your events to load properly.
You'll see the accounts for mail, calendar, and other services added to your iPhone (for example, Gmail or iCloud accounts).
In this list, please check that
If the account is missing or Calendars is turned off, events in that calendar can't be loaded.
If they do, they may be hidden in this app. Please check Settings (bottom left of the main screen) → Visible Calendars.
For details, please see here.
If your events are on the server but haven't synced to your iPhone, this may sync them and bring them back.
If none of the above is the cause, and only if you use iCloud calendars, events can sometimes disappear because of an issue on the iCloud side.
iCloud keeps past copies of your calendars for a period of time (a few weeks), so you may be able to restore them to how they were before they disappeared.
If you notice your events are gone, please try this as soon as possible. After a while, the copy you need will no longer be available.
Restoring returns all of your iCloud calendars to how they were at that time (the change applies to all your devices, including iPhone, iPad, and Mac).
It may take a little while for the events to appear on your iPhone after restoring.
For detailed steps, please see Apple Support.
Restore calendars from iCloud.com (Apple Support)
Note that if you save events only on your iPhone (shown as "Local" or "Default Calendar") instead of in iCloud, this method can't restore them.
So that you can recover them if this happens again, we recommend turning on Settings → Apple Account → iCloud → Calendars and saving your events in iCloud calendars.
As mentioned above, like most calendar apps, this app only displays and adds events that are stored in iOS.
So if events disappear from iOS itself because of an iOS issue, this app can't load them either.
(It may feel like this app deleted your data, but that's not actually the case...)
Similar calendar apps have also seen the same problem frequently since around October 2024, so it appears to be an issue with iOS itself.
This app reads the calendars stored in iOS.
Most likely, another system is overwriting the color.
Sorry for the trouble, but could you please set the color from the built-in iOS Calendar app?
Change the color of the calendar the event belongs to. Go to Settings → All Calendars, select the calendar, and change its color.
This app's icon is fixed and doesn't change with the date.
Because of how iOS works, third-party apps can't change their icon to match the date.
Apple's built-in apps are official apps, so their icons update automatically with the date.
In the event list, swipe left on the event you want to delete and tap the Delete button.
Please turn on notifications for the built-in Calendar app.
Notifications set on iOS calendar events are only delivered by the built-in Calendar app.
Settings app → Notifications → Calendar → turn on Allow Notifications
A spam calendar was probably added without you noticing.
You can fix this by going to Settings → All Calendars and deleting the calendar that was added without your permission.
For any other problems, sorry for the trouble, but could you please report them by email here? Thank you very much.
*A mail account must be set up on your device.