What sort of tile adhesive should I use for a glass mosaic tile?
Generally the glass manufacturer will make the proper recommendation for a suitable adhesive.
Generally the only suitable adhesive has been modified thinset.
Generally organic adhesives haven't worked out.
Lately however, there have been some organic adhesives come on the market that the maker claims is suitable for glass. I've never trusted or used organic adhesives with glass.
So...the best thing to do is to look at a few products and read the instructions for "uses" and abide by the manufacturer's recommendations.