crwdns2934241:0crwdne2934241:0 jaordyna
crwdns2934249:0crwdne2934249:0:
On my Casio Privia there is a function labeled "touch response" (functions are labeled above keys, this particular one is the furthest right function labeled on my keyboard; other models may differ, see your user manual). Press and hold "function" while pressing the affected key (middle C in your case) and choose the "0" under touch response. This fixed it for me.
crwdns2915684:0crwdne2915684:0:
open