https://documentation.vin65.com/Store/Promo-Builder#shipping-type The part about it applying to all shipping types doesn’t seem to be true. Or else if you change shipping strategies AFTER creating the promo that doesn’t define specific types, it breaks it. I’m not worried about it, just pointing it out. If you want to see an order/promo that this happened to I can provide it.
Actually, i think what happened is that the promo did have specific types, which were deleted. And then with it showing no specific types (but having them in the database still), it caused it not to work right. No worries really. Except you might want to look at what happens to those promos when a shipping strategy is deleted.