[C++/Win64]: breakpoints markers (red bullets on the left of the editor pane) disappear while debugging step by step

Environment:

• tool-chain: C++ tool-chain that comes with Visual Studio 2015.
• VSCode 1.12.2
• Windows 10.

Steps to reproduce:

1. Add a breakpoint somewhere in the code
2. Start debugging, and wait until the breakpoint is hit.

Expected result: The breakpoint from step 1 should be visible during the debugging sessions (while we are in the Debugger view).

Actual result: The breakpoint is only seen while we are in Editor view. In Debugger view it disappears. Please note that this issue happens only if we are during a debugging session (we are attached to the process being debugged). If we just switch between the Editor/Debuger views while editing the code, the breakpoints are always seen.

Consequence: If we want to delete that breakpoint while we are debugging by pressing F9 on the same line where it was added, a new breakpoint will be added on the same line! (instead of deleting the old one).