You can change the appearance of multiple selected vector objects by using the Hue, Saturation, and Lightness bitmap effect. Just click Effects > Adjust > Hue/Saturation/Lightness to access the controls.
Tip provided by Pratik Shah, CorelDRAW Master, Graphic Designer & Trainer.
Thanks Mr. Metrailler. Your tip of workaround worked. However, should't it also work as indicated by Shah? (pure vector)