I had to reset three GE Link bulbs and eight Sylvania Lightify bulbs. The reset instructions for both are fairly similar: 5 cycles of the bulbs being on for 3 seconds and then off for 3 seconds.
The first GE Link reset very easily. I tried to reset the second at least half a dozen times but it failed. Had issues with the first Lightify bulb I tried as well. In exasperation, I setup a reset bulb flow in Stringify that controls a zigbee outlet, and I had the bulbs screwed into a 2-prong outlet to E26 socket adapter.
Every bulb reset on the first try - including the ones that had failed in my manual attempts. So, my tip/trick is to suggest using the timer function in Stringify while resetting bulbs - its way more accurate than, "One Mississippi, two Mississippi ......".