So, if you right click a work order in the Help Desk Grid, you're missing those techs; but if you open the work order in the Help Desk itself, you can see them there?
Are any other techs having similar symptoms?
At first guess, it sounds like you may need to rebuild your SearchData indexes. This Community post has instructions for that:
While this Community post has that, plus rebuilding the database indexes. This typically results in better overall performance, but takes a little longer to complete:
Rebuilding the SearchData indexes did the trick. All of the files in that directory had a modified date of May 2014, which is before these two technicians were added to our system.
Thanks again for the quick response.