Stuck Sweet Stout?

Here is a Sweet Stout:AG , for 5gallon
7 3/4lbs Maris Otter
1 lb Roasted Barley
1 lb Vienna
8oz Flaked Oats
8oz Victory
6oz Patent
1 lb Milk Sugar
Yeast: Dennys 1450 Fav

Now I got OG 1.057, but batch was bigger than I thought, 6 gallons. I used 1 gallon too much in the Mash.
Smack Pac of Dennys got real big. Pitched at 70 (no starter). very little activity
Checked 1 week into, was at 1.030.
Primary has been at 68 - 70 consistently.
Checked 3 weeks later, still 1.030. Decided to add another Yeast, with a starter. used the WLP 007, supposed to be fast, high atten. eat through the sweet. Still no activity.
Any ideas on why this would stop at 1.030? My software says it should get to 1.014??

Are you measuring gravity with a hydrometer? 1.030 on a refrac with alcohol will probably be in the teens for FG. If using a hydrometer, what was your mashing temp? High mash temp can result in less fermentable wort. Is milk sugar the same as lactose? That is unfermentable, so without putting anything into a calc, you may have a high FG if you assumed lactose would ferment out.

Software can not predict the FG. If you change the yeast in the calculator, the FG will not change. If you leave it blank, it will not change.

sweet stouts are supposed to have a higher FG because of the lactose. lactose is not fermentable

it’s probably done