I have imported (zipped) ROMs for SNES but when I double click the game in Launchbox all that happens is Windows opens the zip archive.
I can run the emulator standalone, in this case snes9x-x64.exe, and my games work fine. I can also do this from the command line.
The only workaround I have found is to right click a game and select edit, then select the emulation tab, and manually check the box to tell Launchpad to use an emulator.
Hundreds of ROMs, this isn't a suitable workaround.
Here's some screen shots of various settings...
https://imgur.com/jLmVfww
https://imgur.com/bPQL4RA
Launchbox free version 9.5
Windows 10, build 18346