The latest version on the master branch. assets:precompile runs. The ltr and rtl versions of the stylesheets are all present in tmp/stylesheet-cache.
With a LTR language the stylesheet link tag is outputting this:
<link href="/stylesheets/desktop_0eb6bcb9ae52a6f7bcd2c532c6f8f020d1b7a01b.css?__ws=forum.bookswithwings.org" media="all" rel="stylesheet">
This is finding the stylesheet.
With a RTL language the stylsheet link is:
<link href="/stylesheets/desktop_rtl_0eb6bcb9ae52a6f7bcd2c532c6f8f020d1b7a01b.css?__ws=forum.bookswithwings.org" media="all" rel="stylesheet">
This is returning a status of 404. But the rtl file is present in tmp/stylesheet-cache
I also tried setting up a new installation of Discourse and got the same results.
When I apply the changes made in this PR to an older version of Discourse (when you were still accessing the stylesheets in the uploads/stylesheet-cache directory, everything works as expected.