Hello Adam,
The sun triggers seem unstable for some, I’ve seen several posts about it this week.
You can try the Sun Events app as alternative,
and I’d suggest to report your issue also to Athom: Support | Homey
What I don’t get is the use of a 720 minute delay to get the lights to turn off at sunset, while there are WHEN “the sun sets” cards as well?
Also the days almost never have the same length, using a “sun set” card seems more logic?