Is it possible that the polyfill material is burned in the carto? I have no experience with the viscosity of this juice so this is just a shot in the dark. If the juice is thick , it takes a little while for the 100% vg to fully saturate the material and reach the coil. Thus , though the filler material in the carto may have seemed fully saturated, it may not have made its way all the way down. Only suggestion I have is to fill another carto, and let it sit for about 20 minutes and see if the filler still looks as wet as when you started. If not, add a few more drops and wait another 10 minutes or so. Sorry if that was obvious . I don't assume anything when trying to help.
If the above is not the case, then perhaps you just don't like the vape characteristics of Gandalf . Have you tried other naturally extracted tobacco juices that you enjoyed? Perhaps put some in an 808 and try it on your other setup?
BTW I got my ProVari V2 starter kit in the beginning of September and I have been quite happy with both it and the 3.0 ohm Boge cartos that came with it.There are no rules to the voltage you like .If you do fill a new carto , start low (3.7v or so) and just start going up in .1v until you find the vape that suits YOU.