Split screen inaccessible

[SneedoftheWest]

The swipe up from the bottom of the screen with two fingers no longer activates split screen. What it now does is absolutely nothing. I do not use split screen often so do not know when this happened but it is now impossible to use this feature. Assuming it is still available, how does one start it?

[TipsyTrex]

Long press an app in multitasking, you will be able to drop it in the top or bottom half, or in the middle as a floating app

[SneedoftheWest]

My S21 has nothing called multitasking. If I search for it the response is nothing found.

[SneedoftheWest · Accepted solution]

Solved by older 2013 answer, which was completely different than the answer above.