Sorry for the delay in responding, sidetracked by another project.
This is happening in all projects. I'm also seeing that searching for phrases using "" marks is also not working (i.e. "One Two Three" returns no results, even if the phrase is present and a search for just those words (no quote marks) does return the topic).
I'm thinking something's been corrupted in our Help - what files should I be looking at to delete and rebuild to see if this fixes the problem?
Are you testing on the published help or the generated help. The latter is rebuilt every time.
Try in one of the sample projects. Click Open on the RoboHelp Starter page and then click Samples in the ribbon on the left.
If that works, try downloading the demo merged help from my site and generate from that. Test that works.
Post back with the results at that point.
See www.grainge.org for RoboHelp and Authoring tips