Same problem but I have no Embedded MATLAB Function block. Just a simple Script -> Function -> sim(modelname) The moment I put breakpoint @ the function bam!
Error using var_del_run (line 28) INTERNAL ERROR. Failed assertion in b:\matlab\toolbox\stateflow\src\sf_runtime\debugger\sfdb_breakpoints.cpp at line 22: (script->bm.breakpoints).length>(unsigned int)(lineNumber-1)
I do not have or use stateflow and there's no b: drive on my machine, so I am puzzled as for where this error is pointing.
r2014a x64 on a Win7 x64 machine.