System Workbench for STM32

On which OS ?

What do you mean by running your program ?
Are you using the menu Target => Program chip... ?

Or the Debug isn't programming your appli code ?
Can you add -d in openocd options in debugger tab in debug configuration and attach the result log file ?

The previous version was working fine on the L100C disco ?
On which plugin version are you now ?

Can you try a fresh SW4STM32 install ? Installer exe have been updated.

Rgds,
Laurent