Thanks for all the advice and feedback so far.
It seems the issue is probably nothing to do with the redirect, nor Articles.
I set up a new blog, using just Collections, Tags, and Archivist.
Again, the archive links don't work - all the archive links go to a 404 page.
For the archives I'm using this on my archives template page (resource 135):
[[!getPage?
&element=`getArchives`
&elementClass=`modSnippet`
&tpl=`BlogCollectionsRowTpl`
&hideContainers=`1`
&pageVarKey=`page`
&parents=`131`
&includeTVs=`1`
&toPlaceholder=`archives`
&limit=`10`
&cache=`0`
]]
[[+archives]]
Then in the sidebar of all pages I'm using this to give me a list of available archives:
[[!Archivist? &target=`135` &parents=`131`]]
Resource 131 is my Blog container page.
If it click on any of the archive lines, the target URL looks as expected (domain.com/archives/2017/05/) but it just gives me a 404 error.
Any ideas what could cause this?
Thanks
Andy