Setting up JSS on the server side and I've been noticing that the call to sheets.toString call returns nothing for the first request

However on subsequent requests the CSS is available on the server and so content loads perfectly with JS disabled.

Has anyone seen anything like this? I would guess this line is the culprit, but I haven't looked into where sheets are .attached.
As an aside, the react-ssr example (found here) isn't really Server-Side rendering (or at least it's such a simple example it's hard to relate to given that it just generates static content). If I have some time I'll toss up a PR to add one where there is a running web server involved.
It is most probably related to your logic, which does't render stuff on first request. If you can create a simple reproducible example, I can look into it.
We released react-jss 7, check it out.
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We released react-jss 7, check it out.