It worked! Flushing the RunGo cache fixed the problem. I've now completed the 1k tryout. Unfortunately I don't have a time for it (didn't bother starting my watch and forgot to turn off RunGo so my average pace was over 1hour/km). Anyhow, that's all set for my HM on Friday.
Love the way it says "woop woop" in a flat, emotionless voice!
Went out for a gentle stroll yesterday but felt worn out afterwards. I think the previous day's 10k at race pace took more out of me than I realised.