I have the opposite experience. I also run home assistant, and have added the Tradfri hub to my "Home" on iOS. I can count on one hand the amount of times I adjust the one Tradfri bulb I own in the Home app - and it has actually done anything. The only way I have consistently managed to change the bulb's brightness or on/off state is through the official Ikea app - which makes it entirely useless - as I can't automate it.

I do not have this issue with my Hue bulbs, which are running an out of date v1 hub.