There is only one app which can do it, the Repligo reader. Moon reader, WPS office, etc etc cannot highlight text in reflow mode.
Even when I run it via a VM as the server, the highlighted text are still the same in the editor (even though the reflow/rewind has been cleared). After testing, the following fixes is recommended by the official forum: — Add reflow mode back to View mode for the app-wide View modes. — Add the option which will reset the reflow state for a View mode so that the highlighted text will not change depending on the text that is being highlighted. — Do not clear the reflow state from the View mode if the text is not highlighted. — Add the ability to highlight text and the ability to change its reflow state by raindrop from a non-viewer. — Add the ability to change reflow state via click events, such as when the selected text is hit.