Have you tried connecting with bridges outside of the Whonix platform i.e. using the Tor Browser Bundle on standard Linux/Windows/Mac OS?
This would help rule out a Whonix-specific problem. I see the OP had no problem with the suggested method in their Qubes-Whonix platform.
Also, make sure you try a bridge with port 80 or 443 also (:80 :443 at the end of the bridge) to rule out firewall issues.
If you are trying to connect from a censored country e.g. Saudi Arabia, Kazakistan etc. then state-level interference is also possible. This is reported recently on the Tor Project as a problem for bridges in the Middle East, Africa, and Eastern Europe.
In that case, you will probably only be able to connect to Tor using the meek plugable transport, since blocking it requires the state to censor massive domains like Google or Amazon because the bridge is disguised to look like you are talking to their servers.
Using the meek transport in Whonix has not yet been written up in the wiki here, but not sure whether @Patrick has ever had success with it. Probably, since he is a guru at this stuff.
But to use Meek with the standard (non-Whonix) Tor Browser Bundle, follow these instructions here: