I know what the error is, I just don't know why it happens. Sometimes when a like is clicked, it doesn't go through (capturing the member's ID #), resulting in a 0 in the entry, which is why a name doesn't appear. I don't know why this happens, since it seems to work fine like 99.9999999% of the time, then one doesn't get logged.
Could it be a device? Certain browser?
I'm considering just ponying up the money to get the much more featured "Likes" mod here:
http://www.smfpacks.com/likes