From the PADS logic schematic, the design was "ECO to PCB" while PADS Layout PCB was having "On-line DRC" activated.
The components placed at the top layer was okay while the components placed at the bottom layer were having some issues.
The mask pads were locked to top layer and cannot be changed to bottom layer when components were placed at the bottom layer.
Observation : if the "On-line DRC" was not activated, this problem will not exist. When a component was changed from top to bottom layer of the PCB, the associated component pads parameter were changed accordingly.
Please advise how this can be corrected if the layout designed was already done and we need to change all the components mask pads to the correct layer.