King was on Friday morning meant to put the finishing touches to what had become a drawn-out switch to the Midlands club but nothing was confirmed before the FA deadline for registering new signings.
The latest hold up will only further frustrate Aidy Boothroyd. However, the Sky Blues boss will be happy to welcome back Gary McSheffrey after he missed Tuesday's 2-1 defeat at Swansea with a hamstring niggle.
Fellow wide man Danny Ward was forced off with a calf injury at the Liberty Stadium but his withdrawal was more of a precaution and the youngster will be assessed as late as possible.
Striker Freddy Eastwood remains in the treatment room with his knee problem and misses out but Boothroyd opted to remain coy regarding the availability of trio David Bell, Michael McIndoe (both hamstring) and James McPake (shin).