Sorry my mistake,
the formula is =IF(OR(C3="",D3="",E3="",F3="",G3="",H3="",I3="",J3="",K3="",L3="",M3="",N3="",O3="",P3="",Q3="",R3="",S3="",T3="",U3="",V3="",W3="",X3="",Y3="",Z3="",AA3="",AB3="",AC3="",AD3=""),"*",1)
The cells being checked have a formula to pull the data from elsewhere and that is causing the issue. For example D3 as a formula in it =Sheet1!C10