One missing Vocabulary under Sort Criteria. Why? How to troubleshoot?

I am trying to add a taxonomy based filter criteria to a view. In the popup to select a filter I filtered the available options with the word "taxonomy". All except for one of my vocabularies is available as a filter option. The one that is missing is the one I need. Why? It is called "Supplement Brand". Plenty of product display nodes have terms of that vocabulary added to the field of type "Term reference" where I use the "Autocomplete term widget (tagging)".

I have added several relationships trying to get the missing vocabulary to show up as a filter criteria:
"Indexed Node: Supplement Brand"
"(Supplement Brand) Taxonomy term: Parent terms"
"(Supplement Brand) Taxonomy term: Vocabulary"

I looked for a relationship called "Content: Taxonomy" but it is not there. That is also not a filter criteria.

This view is sucessfully using only one filter: "Indexed Node: Content type (= Supplement Display)"
I'm going insane trying to get this view to simply show only product displays from one brand. My goal is to have one page of this view for each supplement brand (or at least a few selected brands).

I would be greatful for ANY help with this. I am worried my views installation (or perhaps taxonomy) is broken. How can one vocabulary be missing? Why does adding relationships that mention it not change the filter criteria options?

Thank you for taking the time to read this. Any response would be a blessing. Let me know if there is any other information I can supply regarding this issue. I have added pictures below to help clarify my situation.

My Vocabularies:

The view Settings:

Available Filters "Taxonomy":

Available Filters "Supplement":