Mbed on ST DISCO-L475VG-IOT01A: debugger never stops on some lines

With this configuration:

platform = ststm32
board = disco_l475vg_iot01a
framework = mbed
debug_tool = stlink

And the mbed blinky example.

Despite the breakpoint, the debugger never stops on lines 11 (and 9) when there is myled = 0; but why ?
see here

We did huge improvement for debugging of mbed OS in PlatformIO Core 3.6.1rc2. Please open PIO IDE Terminal and type pio upgrade --dev. Start build session again. Does it work well now?

I did the upgrade but the problem is still here