Can't access recently open apps.

Every now and then, the button to access recently opened apps just doesn't work as it should. Normally, I would swipe up to access them and they would stay (until further actions are taken). But here, I swipe up to access recently opened apps as I normally do, but it doesn't stay. Then I would have to put my phones launcher as its default, close all apps, then put Niagara as my default again. It works for a few hours, then repeat.