I cannot believe it's been days and no one else has commented. I am also experiencing loss of closed captions. They are completely gone whether using on replay or always on. They worked perfectly before the last 9.4 update. I've reviewed settings and rebooted Roku - no go.
I am also experiencing occasional, albeit infrequent audio drop outs that I have never experienced before the 9.4 update.
Update: today Acorn produced CC as expected. Not sure how or why, but pleased.