[Hugh]

To do annotations using the pen, I have always started by zooming and panning to where I want to be. However, the zoom tool is not able to initiate zooming.  I can work around this by selecting another tool (pen, Txt, stamper, eraser) and spreading two fingers to start the zoom. Then switch to the Zoom-Pan tool, which now works as it always used to.  But as soon as the view is un-zoomed back to normal, the zoom tool cannot zoom without that initial bit of zooming by another tool. 
<Lenovopad TB-X304F    Android 7.1.1    MobileSheetsPro  3.0.6  >
Hugh