Try having Photoshop open before you send file to it from LR.
If my suggestion above doesn't work then we will need more details on what exactly you are doing.
I'm having the same issue. I opened Photoshop 2017.0.1 (just updated to the newest 2017 version release yesterday) then sent 3 HDR photos from Lightroom 2015.8 (couldn't find a 2017 update for Lr yet) via the "Edit In > Merge to HDR Pro in Photoshop" right click command. It opens the first photo, then opens a second but quickly closes the 2nd, then stutters for a bit, then closes the first photo and goes to the opening screen where you can open recent files. The three photos are in my recent files list as if it opened them, but I can't get the HDR Pro screen to pop up. I can open photos in photoshop via Lightroom's "Open as Smart Objects in Photoshop" option, but that's a pain because you have to save each photo as a PSD before you can send to HDR Pro via the "Automate > Merge to HDR Pro..." photoshop option. Definitely a bug in the software.
actually, I think there is something wrong with Photoshop 2017 Merge to HDR Pro. I tried opening each photo in Photoshop, saving each as a psd, then "Automate > Merge to HDR Pro...", Add Open Files, then in a matter of 1 second, It opens a new project, adds the three images on layers, and a bottom empty layer called "Merge to HDR Pro" then closes. I've had to attempt several times to see these details because it happens so quickly.
I'm also getting a pop up window after I send the open files to HDR Pro via the "Automate > Merge to HDR Pro..." that says:
"Are you sure you want to convert colors to a destination document with a color profile that does not match the current RGB working space? Source: sRGB IEC61966-2.1 Destination Adobe RGB 1998 Working: sRGB IEC61966-2.1"
How am I going to put my HDR's together? The Lr method "Photomerger > HDR" sucks hardcore, it offers no control over anything but Auto Align checkmark, Auto Tone checkmark, and Deghost amount None/low/medium/high" and the HDRs look like crap.
Once again this is happening to me. It happened in 2015 and in 2016.
I'm in Lightroom and try to merge to panorama in Photoshop.
Doesn't matter if Photoshop is open already or not.
Open in layers command doesn't work either.
Lightroom doesn't see PS. or vice versa.
What to do?
I never reinstalled before bc LR was a download.
Don't want to move to the cloud or next LR.