Breakpoint not coming adjacent to line number

I am trying to implement an echo kernel with debugging capability without using debugpy. The problem I am facing is that I am able to see the breakpoint in the breakpoint section which is present on the debug drawer but the breakpoint is not getting attached to the line number. I have compared the response with the IPykernel one and it coming out to be exact same. I have also tried the suggestion given in What is wrong in this messaging sequence but still breakpoint was not getting attached. Any help on this is highly appreciated, plus is there any echo kernel available with debugging capability for reference purpose.

setBreakpoints command response:
{‘type’: ‘response’, ‘success’: True, ‘command’: ‘setBreakpoints’, ‘request_seq’: 268, ‘body’: {‘breakpoints’: [{‘id’: ‘1’, ‘verified’: True, ‘source’: {‘path’: ‘/tmp/ipykernel_816348/’}, ‘line’: 1}]}}

configurationDone command response:
{‘type’: ‘response’, ‘request_seq’: 269, ‘success’: True, ‘command’: ‘configurationDone’}