Punch in out issue

This is an issue that I am sure has only just occurred. I have a tricky guitar part which I am pleased wit apart from one phrase. I set up the punch in and out points, however, if I want to hear the existing guitar part up to the drop in I can’t hear the new part when I am using Amplitude. If I activate the monitor I can’t hear the existing guitar part. I feel sure that I used to be able to hear the existing guitar part with the monitor off, then on the drop in the monitored version. Surely I have missed something very obvious.

In my defense I usually record with the Kemper.