Has anyone not been able to lose for 5-6 months and then start losing again?

I've squandered a great opportunity by not following the rules and being stupid. I got sleeved 11 months ago. The first five months, I was losing ok (went from 236-190) but due to poor choices haven't really lost any more than that in the last 6 months. (I haven't gained any back either, but just maintained between 186-190.) How realistic is it that I would lose the last 40 if I recommitted, or have I lost the benefit of the restriction since I'm coming up on my one year? Anyone else not lose for 5-6 months and then start losing again?

There's absolutely nothing preventing you from getting back on track and losing weight again.  The sleeve will always be there and, if you eat correctly for it, you'll always have restriction.  

If you're not already, I recommend tracking everything you put into your mouth with something like MyFitnessPal.  From there, work on getting back to your basics.  Here are mine, but yours might be slightly different.  

1. Prioritize protein and water
2. Deprioritize carbs, especially the refined and processed ones
3. Make the most of healthy fats
4. Eat three meals a day with no snacks
5. Avoid liquid calories (breakfast protein shake is the exception)
6. Weigh portions
7. Eat mindfully and with no distractions aside from real live people
8. Move as much as possible
9. Weigh myself daily
10. Be kind to myself

You haven't been stupid - you lost down to 190 and have maintained.  No weight regain, you've maintained that weight loss.  Now you're ready to go for the last 40 pounds.  

I have a Back On Track Together OH Group that you can join.  

Go back to the healthy habits that you did when you were losing those 46 pounds.  You are over half-way to your weight loss goal.  

Go for it and know that you will do it!