When trying to search the Feedback Activity Log for a specific IP user, no search results are shown, as in this example:
Note that this doesn't work for the Feedback log either, not does it work with other IP addresses. But it works if you put a registered user name instead.
This issue was initially reported here on Village Pump:
http://en.wikipedia.org/wiki/Wikipedia:Village_pump_(miscellaneous)#Feedback_tool_.28again.29
Version: unspecified
Severity: normal
It looks like this is default Special:Log behavior; it only supports searches for existing users & this behavior is not limited to AFTv5.
Judging from the comment added in the code, it appears to be intended (legal reasons not to disclose too much info per IP?)
Below excerpt of the code in Special:Log:
/* Fetch userid at first, if known, provides awesome query plan afterwards */
$userid = User::idFromName( $name );
if( !$userid ) {
/* It should be nicer to abort query at all,
but for now it won't pass anywhere behind the optimizer */
$this->mConds[] = "NULL";
} else {
.. the case where user exists, which does add the clause to the query ..
}This issue is not really AFTv5-related. If it is still something that needs to be changed (although it appears to be intentional), we'll have to pick it up in MW core, as it's Special:Log's default behavior.