When publishing HTML5 from RH2017 to RH Server, my layout appears but there is no content (no TOC, no default topic, etc.). I can successfully publish the same project from RH2020 to RH Server.
Are you are using the same version of RH Server for both? I would doubt that is possible as 2017 is a very different animal to 2020. Check with support if that is the case.
See https://helpx.adobe.com/contact/enterprise-support.other.html#robohelp for your support contact options.
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