Most of the time, unviewable dimensions I've come across are either already shown or shown then erased, are in a note, or are inappropriate based on the view orientation.
Create a new drawing and a new view; it doesn't need a format and try to show the dimension there. I think there's an option to show dimensions in a trimetric; it must be a drawing option, not a config option as I don't see it in the config options list. This should eliminate already-shown and mis-orientation as problems, plus there's no notes so no interference from them.
If it shows there then you can add the new drawing sheet to the existing drawing and see if the dimension remains. If the dimension doesn't survive the transplant then look to see if it is already shown or is in a note. Maybe the view it's shown in is erased.
If it survives the transplant then you should get a more descriptive message when you try to move it to the view you want it in about orientation problems.
Nothing more frustrating then quiet failure; wouldn't a message like 5 dimensions in feature XYZ were available to Show, 2 already shown in View ABC, 1 not shown due to view orientation mismatch to dimension orientation, 2 dimensions shown in selected view. be helpful?