Well now I'm confused, at roughly T-48, MMB is showing most seats available for me to select, with maybe 20 seats greyed out across the entire Y cabin (but in various rows - doesn't look like any entire sections are blocked for me.

But EF shows all the available seats as blocked (apart from 14A, which is available) and the 20ish greyed-out ones as occupied.

What does blocked mean on EF then, if I'm still able to select them in MMB?