Matlab calling a Fortran DLL

I created a DLL with Intel Parallel Studio XE 2019 Composer Edition for Fortran Windows. I'm using it with Visual Studio Community 2015 on Windows 10. I call the DLL from Matlab, and it works great. But when I want to debug the Fortran code and I "attach to process" Matlab.exe, the debugger works fine when attaching Matlab 2016 and 2017, but not Matlab 2019a. Again, when I RUN my Matlab program using 2019a it works fine calling the DLL. But when I try to debug and "attach to process" the Matlab.exe of 2019a, it won't stop at my breakpoint in the DLL source being viewed in Visual Studio. But the other versions of Matlab DO stop at that breakpoint. We're talking about the SAME Fortran program source with the same options! Any ideas would be welcome.