That’s very strange! The stroke order data for this character are correct and haven’t been updated recently, so there must be something going on between that and the writing canvas. We’ll have a look and get back to you!
Here’s what might be going on: Based on how you count strokes, you probably write 阝 with three strokes. It could be that the app recognises your third stroke as the first stroke in 付 instead, of thinking that you wrote 阝 in two strokes. Since we don’t see what the app recognises as what because of raw squigs, it’s hard to be sure based on the screenshot, but this is at least a good guess. Since 阝 is in practice almost always written with two strokes, this is the default stroke order in Skritter.
We definitely should! This seems to be unevenly applied, though, so I’ll work my way through most of the characters containing this component and update them. I have already changed the character we’re talking about here, though. As you can see from my previous response, I thought this was already the selected version for teaching, but it turned out not to be. The three-stroke version is the officially correct stroke order in traditional characters (according to the Taiwan MoE dictionary), though, and it might be correct according to other standards too.
Anyway, sorry for the inconsistency on our part, and thank you for bringing this to our attention so that we can fix the issue!