Text annotation are not showing when I enable Annotation API in adobe embed API ?

When I enable the annotation api in the viewer config. then text annotation icon not showing in the toolbar and when I disable annotation API then text annotation icon showing with which I can write yet on the pdf.

If I permanently disable annotation API, then unable to listen to annotation events that I need the most but when I enable then the text annotation icon is not showing that I also need it.

When Annotation APis are enabled, it looks like in the below image

When  I disable the annotation API, then it looks like

So why text annotation icon is not showing on enabling the annotation API in adobe embed API?

Thanks in advance