How do I create taxonomy terms from an exploded list?
An important caveat thats missing from How to add multiple terms to a taxonomy reference field via feeds? is that the taxonomy terms already need to be defined in the vocabulary that you are referencing in order for feeds tamper to assign the term reference value to the node.

In the past I have created two feeds importers, one that is a taxonomy term processor that just contains the terms to load into the vocabulary, and one that is the node importer to import the nodes and have the taxonomy terms assigned to those nodes.

I may be wrong, but I dont believe that you can import nodes and simultaneously populate the taxonomy vocabulary in one step with feeds.