Hello Goskylar,
We would like to see how we can help you with Split View not working as expected. If you restart the iPad with the steps in this link, does the issue return: Restart your iPad - Apple Support
"How to restart an iPad without a Home button
- Press and hold either volume button and the top button until the power off slider appears.

- Drag the slider, then wait 30 seconds for your device to turn off. If your device is frozen or unresponsive, force restart your device.
- To turn your device back on, press and hold the top button until you see the Apple logo.
How to restart an iPad with a Home button
- Press and hold the top button until the power off slider appears.

- Drag the slider, then wait for 30 seconds for your device to turn off. If your device is frozen or unresponsive, force restart your device.
- To turn your device back on, press and hold the top button until you see the Apple logo."
Cheers!