Hi Remco.
Hmm. I just spent about half an hour stripping out most of the functionality from my solution, so I was just left with one controller and a few test classes, so that I could upload it to you.
Switched to Optimised mode = it now builds and runs.
So then I switched back to my develop branch (i.e. with functionality restored, and around 300 tests), and hey presto, Optimised mode still builds and runs.
Let's see what happens if I close and open VS... yep, Optimised mode can still build. Cool.
OK, let's see if my original bug is now fixed...
Nope. I still get "The name 'service' does not exist in the current context".
Let's see if when I switch back to my "stripped down controller and only a few test classes for Remco" branch, if the same thing still happens... yes, it does. I will upload a solution for you.
Matt