Have you moved the image file? What version of Lightroom? What version of Photoshop?
Moved image files from without Lr (finder on mac / explorer on Windows) opposed to from within Lr is the #1 cause of 'Edit In' being disabled.
Being signed out of PS could also be a cause.
Some Reasons for "greyed out" that I know-
1) The Photo is 'missing' Lr shows a ! on the thumbnail, or a complete folder is 'missing' showing a ?.
2) There is no image selected. (Not often seen, but is possible by Ctrl+D )
3) Lr only has access to a Smart Preview. (Full size original file must be available to Lr)
Friends, I appreciate the advice given re: correct item in registry... no idea how to do that. Suggestions welcome.
just had the same problem.
will try the solution. but have to say: if you ask customers to re-install all the software, this is a major bug and should be handled with a bit more "sh_t, we are sorry"... i am angry right now, because i pay for this software and now i have to go through this....
Have you checked the three points I mentioned on 26/12/2017 above?
They will still apply even if you re-install LrC & Ps!