I tried attaching the most recent log in /nem/nis/logs to this message but I get a forum error message saying "Sorry, new users can not upload attachments".
There's an error message in the log regarding harvesting:
auto harvesting with 'NCMMGLUHLA4Q3DR4QZTZSWWUEXKNOEM3NE6YAUND' -> 'FAILURE_UNKNOWN_ACCOUNT'
The above account is my supernode public remote account address.
Regarding the logalpha.properties, I haven't changed that file.