It wouldn't be the first time a seemingly insignificant thing stops a route. The first I can think of is the soccer match, since Sophia choosing to watch the game locks out the Ellie route, same as not continuing to watch porn when Sophia is in the living room. They're not obvious choices you need to make when playing the Ellie route, but they do matter.
It probably is time a Sam fan writes a walkthrough for his route that we can put in the OP. There's
mine or
Mamonetti's if someone needs suggestions for format.