Hi @Sean_K_Bay,
What happens if you remove the header (the line with "OTU ReferenceTaxon") and issue:
$ qiime tools import --input-path taxonomy.txt \
--output-path taxonomy.qza \
--type FeatureData[Taxonomy] \
--source-format HeaderlessTSVTaxonomyFormat
My guess is the header is presenting some challenges. By removing the header, and explicitly telling QIIME the format of the input file, I was able to get the taxonomy data pasted in the thread to load.
Happy new year!
Best,
Daniel