I’ve only used ZHA with the Sonoff v3.0 and now SilLabs (Yellow) co-ordinator, but some folk reported Z2MQTT worked better for them.
I’m not sure how the IKEA gateway integration works - if it uses a control API to ask an IKEA Zigbee software stack to control items, it might cope better with IKEA wierdness than ZHA or Z2M, but it could also just be a ‘radio on a stick’. (note: There was a new IKEA hub released, and don’t remember seeing updates on the progress to integrate it.)
Annoyingly, I’ve just seen a Sonoff Zigbee door sensor fail a ZHA reconfigure after a dead battery and now doesn’t report voltage level. This suggests some issues are independent of manufacturer, and might be ZHA / Zigbee itself.
If you’re really fed up I’d try:
- the “turn HASS and Zigbee coordinator OFF for over an hour to force a mesh rediscover” trick
- a move from ZHA to Z2MQTT
- a new coordinator, like an IKEA hub (after checking if the new hardware works)
Some X10 kit was flakey, and some pricey Z-Wave kit didn’t work for two years and needed a Fibaro Hub + new firmware - sadly, even with “rigorous certification testing” the complexity of modern network devices means they can be flakey like a badly maintained steam engine!
Personally, I’ve literally destroyed some troublesome devices with a hammer (Sonoff ZBridge, IKEA 1-button remote being one) to prevent my engineering brain wasting time attempting protocol debug on a £5 block of e-waste (properly seperated and recycled, natch 
).
My longer term hope is to replace Zigbee with Thread kit and control via Matter, but the flood of cheap devices using a better designed 802.15.4 radio protocol (e.g. allows multiple resilient border routers) is likely a year or so away.
If you’re interested, I wrote a comparison of different automation standards, and their relative costs - basically, CHEAP FAST GOOD Pick any TWO!