If a train booked to call at Frome skips it via the avoider it will show as delayed between Blatchbridge and Clink Road junctions as the system "loses" the train when it diverts from its booked route. It will also show as delayed if the system detects it hasn't moved for 10 minutes or so. In the later case it stops the automated announcements going off every 60 seconds as another minute is added to the delay.
Thanks. My friend actually arrived ok with little delay, so I'm guessing this incident has been resolved.