This is an issue with both the Roon 1.8 clients for Windows and iOS.
It is no longer possible to navigate to a classical composition from a recording of that composition, EXCEPT if there are more than 2 recordings of the composition in my library. In that case I can click on the disc symbol on the album page and it will navigate to the composition.
In 1.7 this was always possible.
See an example in this screenshot. Only Horn Concerto No. 2 has the link to the composition.