@leocg The workspaces themselves retain, but not their contents.
I am aware of the startup settings and I specifically disabled the "retain tabs from previous sessions" because under normal circumstances this merely clutters up my session: when I start a browser I want to start out fresh.
However, being able to retain one dedicated selection of tabs through the use of a workspace would get you the best of both worlds. Yet things don't work this way: either you retain all tabs (which, IMO, once again makes the use of workspaces kinda obsolete: I'd rather open a new window to browser, do my stuff, then close all tabs in there to also close the window).
Hmm, maybe I should post this into a suggestions forum