I find the autocomplete in jira constantly doing absolutely preposterous things - e.g. I'll be typing out a query like "project != TheirProject" and, when I've finished typing "TheirProject" and hit enter, jira has just barely managed to raise an autocomplete prompt such that "TheirProject", which is correctly spelled, gets "autocompleted" to something like "!=" making my entire query "project != !=". I have no idea what's happening in this case as autocomplete seems to take a completed correct term and turn it to something that isn't even semantically valid. It happens to me in some variety at least once a day.