Old thread, but just in case it’s still useful.
I had similar issues with the esp8266 and ws2812 lights - mainly with the esp8266 rebooting from time to time. My setup was similar (actually using https://github.com/bruhautomation/ESP-MQTT-JSON-Digital-LEDs - not integrated with smartthings yet, that’s why I came here searching ) -
This fixed it - (at the top of the sketch) -
#define FASTLED_INTERRUPT_RETRY_COUNT 0
Hope it helps someone… I was getting very frequent reboots before this… our valentines day decorations (lit-up heart) ran for over a week without crashing with this modification.
-mark