I created a custom logical device with 2 port panels 2 × 10 Gbps 2 × 25 Gbps to be used as a Generic system While creating RackType, I am not able to see this logical device in the drop-down for Generic System. I can see other custom logical devices that I created (which have single port panels) but not this one.

UI has validation logic to restrict a logical device with one panel and port role without generic (generic-to-generic not sensible) when assigning logical device into generics during creating rack. 

To allow a logical device to be visible for selection, a logical device having one panel with multiple port groups (each port group has a different speed) needs to be created.

Workaround: 

1) use a single panel with multiple port groups

2) avoid 'generic' role

If you still need to use multiple panels, then please raise an RFE.