Using pathauto for taxonomy pages I'm using pathauto on a D8 site successfully for pattern type Content using a pattern like this:

[node:content-type]/[node:title]


But I'm not having any luck at all when trying to use it for pattern type Taxonomy term using a pattern like this:

[term:vocabulary]/[term:name]


I just keep getting /taxonomy/term/123 instead of /taxonomyname/taxonomyterm

I have searched and searched and every article I find only covers the tokens for Content, not Taxonomy. I did find one youtube video that covered it in D7 and the pattern was identical to mine, yet his worked but mine doesn't. I've cleared caches and even tried bulk generate to no avail. But Taxonomy (list) pages don't create aliases though, so I'm wondering if that has something to do with it.
Have you actually tried to visit /taxonomyname/taxonomyterm? 

The /taxonomy/term/123 isn't actually a taxonomy page, it is a Views showing content tagged with the term from the URL. It's a separate thing. 

What do you expect to see on that page? Just the term name and description? That should work with the Pathauto as you have set it up. 

If you want to see the content, like that Views page, you can use the Taxonomy term Views, Duplicate it and disable the original just for future reference, and modify the Contextual filters and Path to your preference. 

You will need to add the Relationship to the term so you could use the Taxonomy: Name Contextual filter to get the term name in the URL.

You can also set up aliases for the default Taxonomy term Views so they use names, but I think it would have to be done manually, and isn't at all elegant/smart solution. It make more sense to set up the Views as you intend it to be used.