Hey @MSullivan,
Thanks for the detailed output! Based on your cat command, it looks like your .Rprofile is empty.
You should add this line to it (while using QIIME 2):
.libPaths(.libPaths()[2])
This will make a regular R Studio act weird, so you'll want to remove it if you plan on using R externally to QIIME 2. This isn't a great solution, it's just something that happens to work ok for the moment.
If adding that line doesn't fix your issue, could you follow up by creating a new topic with the --verbose output (or attached debug file) so we can take a closer look? Thanks!