Hi LT0107,
Thanks for confirming. Are your Calendar entries saved to your device or synced with an email account? If they're synced, you may want to try turning Calendar off and then back on. You can do so by tapping Settings > Calendar > Accounts > [affected account], and toggling off the option next to "Calendar."
If that doesn't help, make sure you're running the latest iOS version, as this can often resolve unexpected behavior in the software: Update your iPhone or iPad - Apple Support
Should the above not help, we suggest you contact Apple Support so that they can look into this with you further: Apple Support
Take care.