The symptom you’re describing — bulb flashes briefly but never shows up in Z2MQTT — is probably caused by missing the 6-cycle reset before the 12-cycle sequence.
Check this HA Blueprint here: Ikea Kajplats Zigbee mode — confirmed working via smart plug HA automation that does the entire thing for you automatically.
Just plug your lamp into a smart socket, screw in a bulb, run the script, and it handles the full sequence with the correct timing — no manual counting, no losing track. Works for both older IKEA Trådfri bulbs (6 cycles only) and the newer Kajplats Matter bulbs (6 + 12 cycles). Huge time saver.