few things can be a problem here.
the roadster std design puts the master cyl very low in the car so bleeding has no down hill syphon effect that can be made harder by pipe routeing higher than the master cyl and puting things like hyd brake switchs in a way that thay trap an air pocket/bubble.
a good tip is to prevent suck back as much as possible and if you have an unsealed union it could take all day.
check all your unions are tight ptfe or red grease your nipple threads and bleed the master cyl at its pipe unions first and see how you go.
i have a top mount style pedal box and i just opened the nipples waited for gravity to do its thing and watch for drips at the nipples tighten them all up and it was done
