Is there any recommended fix for this currently (I am attempting hangup and call again, but would like to coach the next agent if necessary).

Showing a Lufthansa short haul flight in Europe, and I'm trying to change the tail end of an existing ticket to tag it on, seems to be available and bookable on the website in both economy and business, direct on two different flights. As well as a dozen different connections.

Agent "can't see" anything in either business or economy, just a single connection via Austrian with a long overnight wait in the airport. Obviously not so useful. She said she also tried to "get it directly" but still "can't see" it.

Any recommendations on telling them what to try?

It doesn't seem to be the phantom availability thing on LH (I think) though these are mostly LH. I can go right through on the website to booking it as part of a round trip.