Debugging when source code is available

R# decompilation is great and I've used it for a long time, especially using Ctrl-F12/Ctrl-B to navigate members etc.

However, I came across the need to debug a third-party library and find that F9 does not work to set a breakpoint.
Instead I have to use Debug/New Breakpoint/Function Breakpoint and manually type in (!)  a Function Name.

So I have two versions of the source code:
The original, in which I can set breakpoints (though the first one is a pain) but I can't use Resharper; and the R# recompiled version in which I can easily navigate but cannot debug properly.

Is that just "the way it is" or have I omitted some configuration somewhere to make it all work nicely together?