Hi,
It’s not you - it likely the end device hardware + firmware.
If you search the forum, you will find many posts detailing issues with IKEA Tradfri remotes behaving in odd and non-standard ways. Basically, IKEA added extensions to Zigbee to allow direct pairing between a remote and a device - and this causes issues, particuarly with ZHA, and some with Z2MQTT.
I’m surprised the firmware update was so quick as it usually takes a day or so to trigger.
The IKEA mains switches are fine, but I’d leave the radio remotes well alone unless you like troubleshooting Zigbee and replacing CR2032. There are lots of threads with recommendations with alternatives like Aqara, Sonoff, etc. The Sonoff 3 co-ordinator has a good name, although there are slightly different versions which act differently with other Zigbee stacks.
CR2032 start at about 3.2V and IKEA remotes die at about 2.9V - which gives lots of life for other devices such as bike lights.
ZHA also has a annoying issue where a battery device looses power, then either doesn’t come back after battery replacement, or looses attributes like battery level. Re-interviewing doesn’t work - factory reset and add new device sometimes does.
I hit a Tradfri single-button remote with a hammer as it only ever paired with a nearby Zigbee bulb, requiring two devices to be factory reset. 
(I hate landfill, but there are exceptions - the hammer put it beyond use to prevent ‘one more try…’)
I’ve heard Z2MQTT is better at handling IKEA oddities, which I can believe as currently a Sonoff door sensor is off-line as ZHA can’t find it after a battery replacement (but at least it lasted several months).
Oh, and always pair the device in the FINAL LOCATION where it will be used. Unlike Z-Wave (which recalculates with mesh every night), Zigbee seems to not like mesh changes, and some devices ignore new router devices right next to them (IKEA 5-button remotes being a ‘favourite’).
If this helps, 
this post!