kernel won't respond to 'attach' debug message

[DavidKutu]

Environment data

Version: 1.60.0-insider (user setup)
Commit: 8dbad73de575e47e127c8b1a4324f2b61257fbdc
Date: 2021-08-27T21:25:29.781Z
Electron: 13.1.8
Chrome: 91.0.4472.164
Node.js: 14.16.0
V8: 9.1.269.39-electron.0
OS: Windows_NT x64 10.0.19043

jupyter: v2021.8.2031173646
python: v2021.8.1159798656

Expected behaviour

Run by line starts

Actual behaviour

nothing happens, cell doesn't even run but the context key thinks we are in run by line

Steps to reproduce:

1. Unfortunately, there are no steps. Just play with run by line, until a cell doesn't run when clicking the RBL button.

Logs

Output for Jupyter in the Output panel (View→Output, change the drop-down the upper-right of the Output panel to Jupyter)

[DavidKutu]

logs.txt

[DavidKutu]

Dupe of #7586
That one has a consistent repro