I’ve sent out the bat signal (duck signal?) to a dev to see if this is the intended behavior. Based on the fact that the taxonomy
query parameter specifically says to use it with the terms
attribute, I wonder if this is simply how PHP’s wp_query
feature works in the first place. I can see why you’d want to use the syntax as you wrote it (I would have assumed that would work too), but it would also make sense if the terms
parameter was necessary since WordPress stores post IDs alongside taxonomy terms, not taxonomies overall.
In any case, I think it’s possible to work around this pretty easily with something like this:
<List terms>
<Loop type=taxonomy_term taxonomy=my_tax>
<Item><Field id /></Item>
</Loop>
</List>
<Loop type=post taxonomy=my_tax terms="{Get list=numbers}">
or this:
<Loop type=post taxonomy=my_tax terms="{Loop type=taxonomy_term taxonomy=my_tax}{Field id /},{/Loop}">
I’ll let you know when I hear back from the dev.