That being the case, the only significant difference I notice is to the lower right side of you image. Can that be explained with the cut off time?
Is there hierarchy in the network and is that on by default when you do the service area. (I think not looking at the picture but just want to be sure).
Can you turn on the Line generation and re-solve for both 10 and 10.1 and check if the lines are being generated in the the area the polygon was covering in 10?