Jupyter error when starting Kernel. Cell not executing just shows * - jupyter

Question

I use a custom kernel manager, which launches kernels as Docker containers.
Recently updated my system, but can't find any relevant Jupyter versions which may affect this:
Tornado 6.2
JupyterLab Version 3.2.9
Custom Kernels
When starting a new Kernel I get:
[I 2022-07-28 10:17:20.946 ServerApp] Kernel started: b2039b53-2ce0-48f1-b327-2b0393a53ff5
[W 2022-07-28 10:17:20.952 ServerApp] No session ID specified
NOTE: When using the `ipython kernel` entry point, Ctrl-C will not work.
To exit, you will have to explicitly quit this process, by either sending
"quit" from a client, or using Ctrl-\ in UNIX-like environments.
To read more about this, see https://github.com/ipython/ipython/issues/2049
To connect another client to this kernel, use:
--existing /connection-spec
[W 2022-07-28 10:18:20.954 ServerApp] Timeout waiting for kernel_info reply from b2039b53-2ce0-48f1-b327-2b0393a53ff5
[W 2022-07-28 10:18:25.473 ServerApp] Nudge: attempt 10 on kernel b2039b53-2ce0-48f1-b327-2b0393a53ff5
[W 2022-07-28 10:18:30.486 ServerApp] Nudge: attempt 20 on kernel b2039b53-2ce0-48f1-b327-2b0393a53ff5
[W 2022-07-28 10:18:35.499 ServerApp] Nudge: attempt 30 on kernel b2039b53-2ce0-48f1-b327-2b0393a53ff5
[W 2022-07-28 10:18:40.517 ServerApp] Nudge: attempt 40 on kernel b2039b53-2ce0-48f1-b327-2b0393a53ff5
[W 2022-07-28 10:18:45.533 ServerApp] Nudge: attempt 50 on kernel b2039b53-2ce0-48f1-b327-2b0393a53ff5
[W 2022-07-28 10:18:50.548 ServerApp] Nudge: attempt 60 on kernel b2039b53-2ce0-48f1-b327-2b0393a53ff5
[W 2022-07-28 10:18:55.562 ServerApp] Nudge: attempt 70 on kernel b2039b53-2ce0-48f1-b327-2b0393a53ff5
[W 2022-07-28 10:19:00.576 ServerApp] Nudge: attempt 80 on kernel b2039b53-2ce0-48f1-b327-2b0393a53ff5
[W 2022-07-28 10:19:05.592 ServerApp] Nudge: attempt 90 on kernel b2039b53-2ce0-48f1-b327-2b0393a53ff5
[W 2022-07-28 10:19:10.607 ServerApp] Nudge: attempt 100 on kernel b2039b53-2ce0-48f1-b327-2b0393a53ff5
[W 2022-07-28 10:19:15.624 ServerApp] Nudge: attempt 110 on kernel b2039b53-2ce0-48f1-b327-2b0393a53ff5
[W 2022-07-28 10:19:20.637 ServerApp] Nudge: attempt 120 on kernel b2039b53-2ce0-48f1-b327-2b0393a53ff5
[E 2022-07-28 10:19:20.960 ServerApp] Uncaught exception GET /api/kernels/b2039b53-2ce0-48f1-b327-2b0393a53ff5/channels (127.0.0.1)
HTTPServerRequest(protocol='http', host='127.0.0.1:8080', method='GET', uri='/api/kernels/b2039b53-2ce0-48f1-b327-2b0393a53ff5/channels', version='HTTP/1.1', remote_ip='127.0.0.1')
Traceback (most recent call last):
File "/opt/conda/lib/python3.7/site-packages/tornado/websocket.py", line 944, in _accept_connection
await open_result
File "/opt/conda/lib/python3.7/asyncio/tasks.py", line 318, in __wakeup
future.result()
concurrent.futures._base.TimeoutError: Timeout
Working case I see, Websocket is opening successfully and:
[I 2022-07-28 10:23:49.698 ServerApp] Kernel started: 84d2de07-7ed5-46ba-8f85-c2bb583be71d
[W 2022-07-28 10:23:49.704 ServerApp] No session ID specified
NOTE: When using the `ipython kernel` entry point, Ctrl-C will not work.
To exit, you will have to explicitly quit this process, by either sending
"quit" from a client, or using Ctrl-\ in UNIX-like environments.
To read more about this, see https://github.com/ipython/ipython/issues/2049
To connect another client to this kernel, use:
--existing /connection-spec
[W 2022-07-28 10:23:53.058 ServerApp] No channel specified, assuming shell: {'header': {'msg_id': '6101c9180e5f11ed969a42010a800005', 'username': 'test', 'session': '6101cc4c0e5f11ed969a42010a800005', 'data': '2022-07-28T10:23:53.054348', 'msg_type': 'execute_request', 'version': '5.0'}, 'parent_header': {'msg_id': '6101c9180e5f11ed969a42010a800005', 'username': 'test', 'session': '6101cc4c0e5f11ed969a42010a800005', 'data': '2022-07-28T10:23:53.054348', 'msg_type': 'execute_request', 'version': '5.0'}, 'metadata': {}, 'content': {'code': 'print(123)', 'silent': False}}
any suggestions?