There is nothing to "enable" regarding the message log. Rather, the log files are in a new location in cDot. In what was traditionally the "/etc" directory there is a sub-directory "mlog". The messages log and a whole ton of other logging is located under this sub-directory. The old traditional "messages" file had been used for the brief moment during node startup before cDot really kicked in for older versions of cDot - you might have gotten one or two lines in an old file before the new logging locations took over. In modern cDot I don't think it's even that much anymore.
Since you are on cDot 8.2+, you have available the SPI web interface to access logging and other data under the node's "/etc" directory, which is the preferred access. You'll see the "mlog" directory just under the "messages" file listed in the web interface. Click through and scroll down to the messages section of the logs.
For anyone looking for details on the SPI web interface, the NetApp referece is here.
Of course, if needed, you can access the files through the systemshell, but you'd likely only need that route in conjunction with NetApp support on a significant problem.
Hope this helps.
Lead Storage Engineer, Consilio LLC
NCIE SAN cDOT | NCIE Data Protection
Kudos and accepted solutions are always appreciated