Maybe XC don't have the stopping rights for Wilmslow station as there are no booked services?
No, this is a Covid-induced change.
Prior to the pandemic, XC had an up morning service to Bristol which called at Wilmslow, a down morning service from Birmingham which called at Wilmslow (1H14) and an up evening service to Bournemouth which called at Wilmslow.
Initially I think the calls were dropped because of potential overcrowding, and they haven't yet been reinstated.
The up morning service to Bristol doesn't run, because currently there are no Bristol-Manchester services, but the other two services run (the up evening one to Reading currently) , are shown to call but not be advertised to call, and in reality they don't call.
I didn't tend to catch these services because, pre-Covid, they tended to be rather busy. However I'd noted but not used the up morning Bristol service as something useful if I needed to get to Birmingham or beyond early.
EDIT Two out of the three XC services which called at Wilmslow did so to free up an extra Manchester-Stoke path for a stopping service in the rush hour in each direction.