Debugging C-Mex function

I struggle to use a debugger for the C-mex S function as described here:

https://nl.mathworks.com/matlabcentral/answers/241291-how-to-debug-mex-file-compiled-with-mingw64-and-g-flags

I am using the mingw-gcc as compiler to create the mex file. Everything goes well (I can connect to the Matlab process and resume it) until when I am running the Simulink S function the breakpoints do not work.

The following versions are used:

• gdb-7.5-tdm64-1 for debugging installed with TDM-GCC Compiler Suite for Windows (GCC 4.7 Series mMinGW-w64 64/32-bit Edition);
• Eclipse version: 2019-03 (4.11.0);
• Matlab 2018b Update4.

Do you have any idea about what might be the cause of the described behavior? Does Mathworks have a proprietary tool to debug C-mex files?