Google Chrome 71.0.3578.21 (Official Build) dev (64-bit)
Google_Caroline.7820.384.0

Still repros. 

An example of this is in the STS settings page itself which can be opened in Settings > Manage Accessibility options > Open select-to-speak settings. 
# Expand the combobox for Color for word highlights
# Use search + mouse to draw the focus ring around the entire open combobox including the default selection still in the main control below.
# Note that all options are read out loud

Expected: highlight moves with the spoken text; items in the expanded combobox are highlighted
Actual: focus remains at the base of the control, the highlight doesn't follow the words