Copying text from a Word doc, pastes as an image

When copying text from a Word doc on a Mac, it pastes into Keybase as an image. When using a non-Word text editor it pastes in correctly as text.

Start by reproducing the issue in Keybase on macOS, comparing copied content from Microsoft Word with content from a non-Word text editor. Trace the clipboard handling involved in both cases; done means Word text pastes as text while the existing non-Word behavior remains correct.

Written by the indexing model from the issue text.