Can you upload a Screen Shot of iClone showing the situation?
In this Screen Shot the Shadow is set to Drop Shadow - no shadow can be seen on the Floor:

In this shot the Shadow is set to Self Cast Shadow and does show on the floor, but not outside it:

Are you sure that your Shadow settings are correct?
Gerry
System: Win 10 Pro (21H2), Asus X99-E WS, CPU i7-5930K -3,5 GHz, 32 GB DDR4 2666-16 RAM, NVidia GTX 1080 Ti GPU - 11 GB VRAM(Driver Studio-536.99), Samsung 850 Pro 512 GB SSD, 6 TB HD storage.