I don’t understand the purpose of this and why in one job there would be something blocked for me to see (especially when the lightbulb is still clickable etc). It would be handy to know ‘why’ it is blocked out (maybe through a popup message or something) unless you can explain it better to me.
Available workspace Layers which are not present in the current job are "hashed out".
This situation only occurs when there are "multiple different jobs" present and open in the workspace. The hashed out layers used as a "visual aide" for layers that do not exist in the current job. For example if you were to import a 2 layer PCB design, and then import a 4 layer PCB design -- the second job (containing the 4 layer PCB design) would not have any layers "hashed out"; however the first job (with 2 layer PCB design) would have metal layers 2 and 3 hashed out - because they do not exist in the current job.
There is an option to control how the "hashed out" layer appear called "Layer Display" (menu: View | Layer Display).
I would recommend that you use Show Layers: All -- which will just display all layers normally - whether they are used or not.