Answer:
The "Detailed Results" entry in the Results navigator of RF‑CONCRETE Members or CONCRETE is only displayed if "a" certain result type has been selected (for example, As,req,above).
When displaying several results (for example As,req,top and As,req,bottom), the "Detailed Results" entry is no longer available.
The detailed results refer specifically to one calculation (for example, As,T) and cannot be generated for several result types at the same time.