Track user > Activity error

[a10]

Wrong value type sent to the database. IPv4 or IPv6 expected.(ip_list)

-------
93bae4c384dab8c9372beac3e4d194b2
https://www.*/forum/index.php?

action=profile;area=tracking;sa=activity;u=4
/customers/*/httpd.www/forum/Sources/Profile-View.php (Line 2101)
Backtrace information

Type of error: Critical
Error message Select
Wrong value type sent to the database. IPv4 or IPv6 expected.(ip_list)
Function: trackActivity

----

    #0: smf_db_error_backtrace()
    Called from /customers/*/httpd.www/forum/Sources/Subs-Db-mysql.php on

line 311
    #1: smf_db_replacement__callback()
    Called from unknown on line -1
    #2: preg_replace_callback()
    Called from /customers/*/httpd.www/forum/Sources/Subs-Db-mysql.php on

line 409
    #3: smf_db_query()
    Called from /customers/*t/httpd.www/forum/Sources/Profile-View.php on

line 2101
    #4: trackActivity()
    Called from /customers/*/httpd.www/forum/Sources/Profile-View.php on

line 1920
    #5: tracking()
    Called from /customers/*/httpd.www/forum/Sources/Profile.php on line

813
    #6: ModifyProfile()
    Called from /customers/*/httpd.www/forum/index.php on line 191

[a10]

Update: seems to work ok now (on default theme). So 'probably' related to testing out (2.1) themes. Also got lots of other strange errors with a few themes, so time may not be ripe yet to move away from the smf default looks :O)