Vertical displacement after Phase Unwrapping

Hello everyone,
I would like to have the vertical displacement after the Phase Unwrapping. As I have read here, after the phase unwrapping I used bandmath to create a new band by applyin this relationship

and then I perform the phase to displacement and the terrain correction (saving the product as GeoTIFF-BigTIFF)
When I open my product on QGis, however, it’s like I haven’t applied the formula, and moreover, if I try to extract the band of vertical displacement to perform the phase to displacement operator, the operation fails because it doesn’t read the band as it was an unwrapped product.
Does anybody know how to have the product? Thanks in advance to who will help.