1.5 FULL / V3
Ah, you see, that explains a lot. This is then not VST 2, but VST 3 version.
The program change from midi does not work for VST 3 plugins.
For Live 12 there might be some change/issue(?) about plugins listing. When VST 3 and VST 2 plugins are found, then somehow VST 2 is not on the list shown even, but VST 3 only. To have VST 2 listed, the VST 3 (and/or AU) should be removed.
If you are sure you still want to use VST 2 version of The Legend, please remove these plugin files:
/Library/Audio/Plug-Ins/VST3/Legend.vst3
/Library/Audio/Plug-Ins/Components/Legend.component
Then rescan plugins in the Live 12 and The Legend VST 2 should appear.
Please note that in the future only Audio Unit and VST 3 versions will be availalbe on Mac for our new plugins (and possibly updates as well).