From a user's email:

I've been playing with Chrome settings with the Select and Speak option and have gotten some different anomalies depending on them. I had update this morning and restarted hoping everything would work but ran into the same issues I'd been having until I started adjusting settings and was able to get Select and Speak working using both a mouse and the trackpad.
 
Some of the things I changed was:
Slowed the Touchpad Speed down one notch from the fastest setting
Turned off Enable auto repeat in keyboard settings
My Display size is set to 1366x768
I cleared my browsing data
Under Accessibility Settings turned off Show large mouse cursor
 
 
What I'm seeing now is I can drag a box around text while holding down the search key and it will consistently select what I'm trying to grab. Sometimes I've needed to keep holding down the search key for a moment when it starts reading otherwise it will stop. I can Search - click on a line of text and it will read and stop.
 
I'll continue to test it off and on today as I'm presenting at the PATINS conference in Indianapolis on Wed & Thur and plan on showing the feature (along with other stuff of course) in my sessions.