Google calendar doesn't sync

I use google calendar and one of my calendars within google calendar does not sync to my android phone. The calendar shows in google calendar, and syncs correctly with my desktop software (Fantastical for Mac). On my phone, I can see the calendar under Settings > Accounts and Calendar folders, but the calendar is greyed out. So the phone know that the calendar is there, but is not downloading the events. Does anyone know how to 'activate' this? (NB I have quite a few calendars withing Google calendar. Is there an upper limit?)

Thanks

(PS Device = Blackberry Keyone).