What is Known Issue?
A fault or defect in a system or machine that has been documented, but not yet fixed. A "known issue" differs from a "bug" in the sense that "bugs" are unknown, or at the very least undocumented.
"Customer Service, how may I help you?"
"Oh my god! I bought your new product and when I turned it on it began systematically hunting and killing my friends and family!"
"Yes, that is a known issue."