Cannot add annotation to a State Timeline panel

I am using version 8.3.4 and have found that I can add annotations to all panels except the State Timeline panel.
I found a similar topic (issue 35424) that seemed to indicate this issue had been fixed in release 8.1.3 but it seems that is not the case?
Is there possibly a setting that I need to change?

Hello, I am looking to same feature.
After a look to issue 35424, annotation creation has been solved but, as far as I can see, only for “Graph” panel.
Please let me know if you have been able to put annotation creation on State timeline panel