See this exception: https://www.irccloud.com/pastebin/P7P6BdpM/
EL records containing nested data are being logged to disk, but are not mirrored into MySQL. @AndyRussG says that it should be as simple as quoting something during json encoding.
@ellery: Please note that you'll be pulling banner history records from the EL log files in the near term, rather than querying MySQL.
See also T112926