It’s being challenged, isn’t it?
Yep, so we shall see.
Up to this point, though, states have been able to control how electors vote.
Control, but not dictate. In the case you cited, the state was mandating that electors follow the will of the voters of their state, not the aggregate of voters nationwide. In the case of the compact, state legislators are telling electors WHO to vote for, even if a candidate got zero votes in that state.