I experienced the same issue in Microsoft Dynamics 365 Version 1612 (9.0.51.6), and fortunately, I was able to resolve it.

You can use the following URL format:

/main.aspx?web=true&pageType=webresource&page={AreaId}&area={SubAreaId}

You can find the AreaId and SubAreaId in the properties panel on the right side of the Sitemap Designer. If the subarea is already registered in the sitemap, you can also identify the IDs using developer tools from the top navigation bar, as shown in the screenshot.

The web=true parameter is essential - it enables the top navigation bar, and without it, the redirect won't work properly.
Also, all three parameters pageType=webresource, page={AreaId}, and area={SubAreaId} must be included together for the redirection to function correctly.

I understand this post is quite old, but since some users are still working with older versions, I wanted to share this solution in case anyone else is facing the same problem.