Just for clarification, we have tested the V18 with the chrome extension and it does not work if you do not have the extension already set up and running in the Chrome client. We were not able to test the upgrade, however, in the situation where you are connecting to a 3CX extension where the Chrome extension was not previously connected to, it asks you to activate it in the Web Client. However, there is nowhere that we could find in the web client for V18 that will allow you to activate the chrome extension. As we have no access to test the upgrade path and see if the chrome extension will continue to operate, we will be delaying the V18 update and doing an information campaign with our users to get them moved to the Windows App first.
Now that the side item is addressed, back to the original question.
We have done some more testing on the recording and have found it a bit hit and miss. Sometimes it records the whiteboard and sometimes it does not. I have not been able to nail down an exact scenario that will duplicate the issue every time.