As stated, the new, 1.x.x version is missing some components as compared to legacy version. As far as I know, the creators are working on missing components, which would come in future updates (I am not sure about ‘Solar Envelope’ specifically). As for old ‘Item Selector’, I think you should be able to use it with the new components.
You can also have both, legacy and new, LBT components installed at the same time. These are placed in different tabs in gh ribbon now.