I have verified this issue on two different Windows systems (I don't know about Mac). This is a known issue.
Problem:
In LR when multiple images are selected and then the follow command is used:
Edit in > Open as Layers in Photoshop
Images are opened as layers in Photoshop as normal but many Photoshop commands are grayed out.
The workaround is to open Photoshop before opening LR.
It is also true for WIN if you open One image and wish to do an Edit content-aware fill. It will be grayed out unless you have previously opened PS. (Then it works fine.)
This problem was just recently fixed a week or so ago in PS Version 20.0.2