I downloaded the msvc 11 precompiled binaries from https://www.allegro.cc/files/ at the time it was 5.0.8 but I see now a new(stable) release is out.
Linking to the allegro-5.0.8-monolith-md-debug.lib and have the equivalent .dll.
I'll download source(5.0.9) from the http://alleg.sourceforge.net/download.html and build it and see if it remedies the situation and I'll update this post with the result.
edit Also I tried your suggestion no luck and your example for me produces the same result as I've been having. I feel like you're onto something with the whole allegro setup thing, I thought I'd get away with being lazy and use some precompiled binaries. However something tells me building it locally will probably fix this.
I built 5.0.9 from source using the msvc 11 compiler.
Didn't resolve the issue it's still there.
Maybe I should try 5.1.X although I doubt that's the issue anymore.
Tried getting glew to play nice with Allegro(dirty I know but running out of options) couldn't get it to go.
Not sure where to go from here and help/ideas are appreciated.
It looks like it does, but just to be sure, Allegro does manage OpenGl extensions in Windows correct?
I overwrote MS's GL*.h files, with new ones of the equivalent version and this solved it. I'm still not sure what happened(if they got corrupt or what) or how but at least it's a thing of the past now.