Installed tab doesn't mirror installed plugins
I might be missing the point of the installed tab... but mine is populated with uninstalled plugins with the "install" button intact. Doesn't seem to be any difference between the two tabs.
I've uninstalled and reinstalled.
Sierra 10.12.4 (16E195) Toolbox 0.5.1 (051)

same for me toolbox 0.5.1 sierra 10.12.2
Ditto! Doesn't work for me. Toolbox 0.5.1 Sierra 10.12.4
+1 0.5.1 Sierra 10.12.4
Same with me Sketch Toolbox 0.5.1 OSX Sierra 10.12.4
Same. Sketch version 43.2, macOS 10.12.3, Toolbox 0.5.1.
There's half of a dozens of us!
Well I switched to Sketchpacks as that tool is working.
Same
I am getting the same problem plus it crashes on opening now and shows up blank if it does load. Thanks much for this thread recommending sketchpacks, had no idea about that one.