What complications with a gastric sleeve could cause vomiting and nausea (worst in mornings) 10 and a half months post op?

Persistent nausea and vomiting nearly a year after sleeve gastrectomy is not typical and should be taken seriously, especially if it interferes with daily life. The fact that symptoms are worse in the morning and improve once you eat suggests that acid or bile reflux, delayed gastric emptying, or irritation of the sleeve lining may be contributing factors.
Even with a normal endoscopy, functional problems can still exist. Some patients develop severe reflux or hypersensitivity after a sleeve, and in others, subtle narrowing or twisting of the sleeve may not be obvious without specialized imaging studies. It’s also possible that excess acid production overnight is leading to the morning nausea and “foam” vomiting, which sometimes represents accumulated secretions rather than food.
If medications have not provided relief, further evaluation is needed. Tests such as an upper GI contrast study, pH monitoring, or manometry may give more information about how your stomach is functioning. In cases where severe reflux or functional problems persist despite medical therapy, some patients ultimately require surgical revision, often converting the sleeve to a gastric bypass, which can significantly improve reflux and related symptoms.
I strongly recommend ongoing follow-up with your bariatric surgeon or a gastroenterologist who specializes in post-bariatric care. Persistent nausea and vomiting is not something you should have to live with, and with careful evaluation, there are often solutions that can relieve symptoms and improve quality of life.

Unfortunately some patients experience this issue after any of the bariatric procedures.  Taking antacids, anti nausea meds do not really help long term.  Some bariatric surgeons call it "the foamies".  The worse cases I have seen, the patient comes to the office with a plastic cup because they have to be spitting all the time.  A lot of the times there is a stricture that you can see during endoscopy.  Some times the endoscopy is normal because it is a functional stricture.  The best option is to revise the sleeve to the gastric bypass.  I have done it several times on my patients with good results.  Consult with a bariatric surgeon in your area.  revision may be your best option.  

From  your description it sounds like GERD symptoms you are describing, which is not uncommon after sleeve.... maybe antacids would help  also need to really make sure there’s no anatomical issue like hiatal hernia or retainer gastric fundus, or stricture in the middle of the stomach sleeve. Assuming no anatomic issue, standard gerd treatments should help. If it gets worse, converting to gastric bypass might Help considerably