VST Applications not installing despite installation process saying they have been

Hi all - I am an Ableton user and am trying to install some plug in VST's - these have been downloaded as dmg or pkg files and installed in the usual way. All seems fine, however, after running the installation process, the VST's cannot be located and a search of my Mac does not show them as installed anywhere. When I try and install again, it shows the relevant files as being "upgrades" - I think this means that the Mac thinks they are already installed. I am at a bit of a loss - I have upgraded to Mojave, tried safe mode, unplugged everything, still nothing works. Has anybody else experienced something similiar? thanks