Begin with a forced-restart of your iPad - as this will often clear an isolated software issue:
Force restart iPad (models with Face ID or with Touch ID in the top button)
If your iPad doesn’t have the Home button, do the following:
- Press and quickly release the volume button nearest to the top button.
- Press and quickly release the volume button farthest from the top button.
- Press and hold the top button.
- When the Apple logo appears, release the top button.

Force restart iPad (models with the Home button)
Press and hold the top button and the Home button at the same time. When the Apple logo appears, release both buttons.

Next, if the problem remains, force-close all open Apps from the App Switcher page...
To expose the App Switcher, it is necessary to swipe upwards with your finger from below the active portion of the screen, to the middle of the screen - and pause briefly - before lifting your finger. Once visible, open Apps can then be closed by swiping the corresponding App thumbnail off the top of the screen.
When all open App windows have been closed, restart the iPad as before.