Relatives in SC attend a mixed race evangelical church (not Baptist) and sing in the choir which is also mixed race.
They say that while at the church, there is mingling among the races, but if there is a choir social gathering at a white person’s home rather than at the church, the blacks will not attend.
Is this the case at your church?
Maybe it’s just a vestige of the old south.
There are some blacks who won’t attend outside of the sermon, but few. Those that attend generally love Jesus more than a skin color. That includes other events.
If one of the Blacks in your chorus were to hold a social gathering, would the whites attend it at his or her house? Perhaps there is an abcess that needs puncturing.