In working with making annotations when in pdf reflow I am finding that the menus (on the bottom menu bar) hang sometimes. EG. -- choose pencil & a color -- menu hangs (stays open) and prevents you from writing a note. You have to choose another menu icon (on bottom) or toggle out of annotations (from top menu) and then toggle back on to resolve it.

I haven't reported this, yet, as I want to be sure I am not experiencing my own user issues, first.