Zoom Doesn't Follow Cursor when Typing with Smart Keyboard on iPad Pro and IOS 11.1.1 in Microsoft Word

Low Vision Accessibility on Apple Products

Zoom Doesn't Follow the Cursor when Typing in Microsoft Word with the Smart Keyboard accessory on an iPad Pro 1st generation running IOS 11.1.1.
We've updated to the latest version of Word, and have signed into Office 365.
We've turned on Follow Focus under Zoom settings.
We've also tried turning on Smart Typeing, although I think this is only relevant if using the onscreen keyboard. In any case, it made no difference.
When my wife writes in the body of an email, Zoom always follows the cursor, but when she types into a Word document, Zoom stops following the cursor when it goes outside the zoomed-in area, so she has to keep re-positioning the zoom window.
She says that Zoom used to follow the cursor in Word, but I'm not sure of the environment at the time. I'm a VoiceOver user myself.

If this turns out to be a bug in Word, please can someone advise on the correct procedure for reporting it to Microsoft?
Can anyone suggest anything else we can try?

Many thanks.