Recipe switch from Extract to Partial Mash - ABV change with specialty grain?

I posted this in the BeerSmith 2 Questions section also, I hope I'm not breaking a rule by posting here too, but my question concerns a brew I am about  to start.

I entered the following recipe that I found for a hoppy red ale as an extract recipe:

2.0 oz black barley (500.0 SRM)
8.0 oz Caramel/Crystal Malt (60.0 SRM)
1lb Carared (20.0 SRM)
6lbs Amber liquid extract (12.5 SRM)
+ hops (amarillo, centennial) and WLP001 yeast

When I entered the recipe for the purpose of a 5 gallon extract brew, the ABV and OG was at the low extreme on the gauge (3.7% and 1.037) and the bitterness at the high extreme (59.0).

Just for fun I wanted to see what the calculation would be if I switched the type to a partial mash. The values then looked normal (OG 1.051 and ABV 5.1%).

If I am only using specialty grain yielding non-fermentables in the steeping process, how is my ABV changing from extract to partial mashing?

This is only my second batch, please enlighten me.

In extract brewing, the specialty grains are steeped, not mashed. Most of the time, specialty grains are not enzymatically active. Steeping extracts color and flavor, but little to none of the starch becomes sugar.

In mashing, you're still steeping, but with enzymatically active malt, like pale 2-row malt. In your case, the Red-X is active. This brings out more from all of the malts, increasing your gravity and the color/flavor punch of specialty grains.

Thanks, I didn't know that the Red-x is active.