Potion effect icons not showing on screen

When you are affected by an ambient effect or potion via drinking, splash, or arrow tip, etc., the corresponding icon does not appear on screen.

Example: I did a series of Trial Chamber runs with the Bad Omen effect, and, while the chamber cages still reacted to the effect, the icon showing I was under the potion’s effect did not appear in the corner of the screen at any time. Likewise for while mining in the Nether, the icon showing my Fire Resistance effect did not display, so I did not know when the potion wore off and I would have to drink another.