Visits appear greyed out on the visit screen when either the client record or carer record linked to the visit is inactive.
This is by design, allowing you to isolate these visits and investigate whether an inactive client still has visits assigned to them, or whether an inactive care worker has been scheduled to complete a visit.
To reconcile these visits, identify whether the visit is greyed out due to the client or the carer, then either remove the visit from the client or assign a new carer to the visit.