Hi @thermokarst,
Thank you for the response! After some testing, I discovered that it was due to my local settings for default channels for Conda in my .condarc file (I'm a long-time conda user, and I had to manually set them a while ago to overcome some older channel priority issues for R packages as they migrated across various channels). Simply deleting the default channel override in .condarc completely solved my problem and I have successfully installed Qiime2.
Thank you!
Tim