On Jan 19th, we had the LAPLAPL rotation on the Magic, with early dining.
The first evening was listed as 'casual dress' on the front page of the daily Navigator right under the picture of the Magic, and also on the last page under dinner, so no jacket even in Lumiere's.
The last evening was listed as 'jacket recommended' for Lumiere's in the small print on the last page of the Navigator in the dining section. I went with a jacket, but I was definitely in the minority view and a few men wore jeans. We had occasion to walk past Lumiere's during the late seating for dinner and jackets were in the minority there also.
If you count an evening of dinner at Palo's, you'll have an additional occasion to wear a jacket too.