Annnnd... I fixed it! I think the issue was that I had two separate versions of PCSX2 installed, because TimeSplitters has mouse injection now.
I think the plugin got confused because I named that custom version "PCSX2 TimeSplitters Edition". I'm not sure how the plugin finds/connects to the emulator, but I renamed that custom TimeSplitters emulator to not have "PCSX2" anywhere in it (inside Launchbox) and then rebooted it. Now I can the configurator tool again - woohoo!
Just wanted to share, as this might help others solve the problem as well. ?
I'm having the same issue. The plug-in worked about a month ago, but after a few Launchbox updates, it won't show up in the right click menu anymore.
I've tried installing a fresh copy also. (Yes, the one here on the forum, not a github repo.)