I just upgraded from 2012 to 2015 both free editions and I've had some stupid hiccups with compiler options and linker options but since moving I'm finding a runtime crash that has probably been in my code for a while but haven't had any issue with till now.

Anyway when the crash happens I have no debug variables, but if I put a breakpoint on the line of code I do get debug variables (This is a function called every frame). Clearly it knows about symbols and I'm running in debug, but barely anything is showing up. Any ideas? I'm going back to 2012 for now and hoping this gets my variables back and maybe it won't crash.

Can you break before the crash and then step until it occurs?

Sounds like stack corruption (e.g. a memset that's going out of bounds and trashing your call-stack) -- this can really screw over a debugger.

In the compiler's code generation option for debug, make sure all the optional debug extras are on, such as "basic runtime checks" and "buffer security checks" etc... Also consider looking into Windows application verifier, which can be great at helping track down subtle bugs like this.

Think I got a lead on the issue. Very well could be stack corruption.