Thanks for replying, ginasdad, and that additional info, it really helps! Since you have checked to related settings, the next step is to make sure your iPad is fully up to date:
Update iPadOS
Also, if you haven't already, force close the Calendar app and restart your iPad and then test your issue again:
If an app on your iPhone or iPad stops responding, closes unexpectedly, or won’t open
Next, so we understand the situation better, do you have any other devices like an iPhone or Mac, and do alerts work as expected on those devices? What account(s) do you have setup in the Calendar app on your iPad? Does this happen with a specific account?
Have a great day and thanks for using the Apple Support Communities!