I had been having problems getting Photoshop to run through integrations with Shotgun. Maya and Unreal worked just fine.
When I created a new project, Photoshop worked.
When I then added Unreal ( using https://github.com/ue4plugins/tk-config-unreal.git from Adv Proj Setup) Photoshop stopped working. It can now not be launched from any of the integrated applications, however Maya still works and I now have access to Unreal.
Has anyone had this issue occur?