We are having a similar problem. However, we are still using RH7 and publishing to the server. We sometimes get search results displayed and other times the "no topics found"...for the exact same search term! We too were wondering if it had something to do with the server...will the instructions provided for RH8 apply to RH7 as well?
I've been all through the forums looking for solutions and it appears that this is a very global problem for both versions. I've been authoring in RoboHelp since version 2 and have never really had this issue popup before. What is so different with version 7 (than say 5) that might be causing this issue?
Thanks for any suggestions!