One quirk of serial debug is that the debug code is injected at compile time in a temp folder. The debug code is always injected at the end of the breakpoint code line. If the code line is an "if()" then the debug code is injected inside the "if()"

Therefore your breakpoint is not being hit because the "if()" does not evaluate to true.

Move the breakpoint location up two lines and it will work. Serial debug breakpoints do not have to be placed on a valid line of code, they can be placed on empty lines too but not on commented code lines.