Source code not displaying during SDBG

I have used FTN95 and SDBG for many years without issues. I have just reinstalled Windows 11 Home and all my apps, including FTN95 v 8.7, on my present PC - something I have done several times before. Everything works as normal except SDBG. Running any FTN95 program compiled with the usual debug options, SDBG shows the usual window 'Silverfrost Win32 Debugger', whose menus and toolbar work as normal, and the 'Call Stack/Status' subwindow shows. But no source code is shown, with any of my Fortran programs. I have deinstalled and reinstalled FTN95 a few times with no effect. What could be happening?

If you are creating a 32 bit (Win32) application and using Windows 11 version 24H2 then there are problems with underflows. You should upgrade to 9.10 or follow the instructions here... https://forums.silverfrost.com/Forum/Topic/4536

Thanks for the reply. My Windows 11 version is indeed 24H2. So I have just bought the upgrade to FTN95 v 9.1. However, after deinstalling my former FTN95 version 8.7 and installing 9.1, the problem remains exactly the same as before on all my programs - They compile and execute as usual in release mode, but in SDBG mode the debug window behaves normally except that it displays no source code.

Are you sure that the executable was compiled using one of the debug options such as /DEBUG or /CHECK or /CHECKMATE?