Calendar app display bug when switching between calendar and any other app.

On my iPad Pro 3rd gen, whenever I open the calendar app, swipe up from the bottom to switch to another app that's open in the background (without closing the calendar app), then do the exact same thing to switch back to the calendar app, the calendar encounters a weird bug. One of the icons in the top left (usually the inbox icon) will be highlighted as if it's been pressed, and if I swipe to try and view a week other than the week currently being viewed, there will only be a blank calendar. It will even be missing the lines separating the days and hours. I won't be able to see any other week until I click on one of the icons in the top left such as the inbox icon and then deselect that icon. This happens instantly and every time without fail as soon as I switch to another app while leaving the calendar app running in the background. I've tried restarting my iPad many times. It's so annoying that I pretty much never leave the calendar app open in the background anymore which I'd like to do. Please help!