Solution
Breakpoints with white color "STOP" symbol indicates the station options setting for breakpoints are disabled.
There are two ways to enable or disable the Station Options setting for breakpoints,
Station Options Settings
In TestStand Sequence Editor Menu bar, go to
Configure>>
Station Options>>
Execution>>
Enable Breakpoints. Check the box to enable and uncheck the box to disable.
Programmatic Settings
Use
Statement Step, in the Expression box, input the following expression
RunState.Engine.StationOptions.BreakpointsEnabled = True
You can set it to True or False to enable or disable the breakpoints respectively.