Bonjour , problème de liaison entre Lightroom et photoshop

Grey 'Edit-In' menu may be caused by-

1) The photo is 'missing'. Lightroom does not know where the original photo is stored- it has been deleted, renamed, moved, by the OS outside of Lr.  Grid view thumbnail is showing a [!] on the border? (or possibly a corrupt file)

MISSING PHOTOS

2) You are using Smart Previews and the original file is not connected to the computer or available to Lightroom. (eg. external usb drive not connected). Plug in the external drive- check that it is using the same Name/Letter as before. (Also see the link for Missing photos)

3) Lightroom and Photoshop are not linked correctly in Registry/plist.  See this link- (ie. Re-install as suggested by @TheDigitalDog )

EDIT IN Photoshop command missing

When the 'link' between Lightroom Classic and Photoshop has issues, one of the first things to try is this:
1. Use the Adobe Creative Cloud application to uninstall both Photoshop and Lightroom Classic, and when asked, keep preferences. 
2. Install Photoshop first, then Lightroom Classic. The order is what is very important here.
Better? 

Your issue can usually be resolved by reinstalling Photoshop.