In the same folder where your VST file is located for the Nebula that logic is loading, there should also be a xml file with the same name (someone correct me if Mac's use different data files than xml). For example, if there is Nebula3 Reverb.dll (or whatever the mac equivalent of a dll file is), there will be a Nebula3 Reverb.xml file. If you open up that file with a text editor you will see an entry called DATAPATH. I'm on Windows, and my Nebula3 Reverb.xml file has this DATAPATH entry:
<DATAPATH> c:\nebulatemprepository\ </DATAPATH>
Within that directory, in my case c:\nebulatemprepository\, there are your Programs and Vectors directories (at least it is on Windows). The Programs folder is where the n2p files go, and the Vectors directory is where n2v files are placed. I see you are on mac, and I do not know that directory structure, but there should be something similar. If you find your Programs and Vectors directories, are there anything in them? That is where Nebula will look for your presets. If they are empty except for the INIT files, then that is your issue. If those directories are full of files, I would suggest opening a Support ticket to allow Acoustica to troubleshoot.