Wheatley doesn't ring after the number of bells has been reduced

[hillwithsmallfields]

When I've changed the tower from 8 bells to 6, and press "l", I hear the "look to" announcement, but Wheatley doesn't ring anything. (The second is assigned to me, Wheatley has already "filled in" on all other bells). Also, on switching the tower back from 6 to 8 bells, Wheatley just rings up to 6.