I traced it down to a problem in environment variables. The Everything process is not including a change to the environment. This application depends on these variables, so it doesn't work.
The sequence of events is...
- Start Windows
- Everything starts (service and minimized to notification area)
- A script runs, which changes the volatile environment
- The script also uses a command to set a dummy variable in the user environment. This action "informs running programs that the change was made, prompting them to regenerate their environments. Programs that support this feature [...] update their environments when they receive the WM_SETTINGCHANGE message"
- I search for something in Everything
- I right click, Send To the application