Hi,
I got similar issue
Time: 1 mins ago -- Tue, 22 Nov 16 05:36:16 +0000 -- 1479792976.147300 in Unixtime
Secs since last hit: 0.2199
URL: https://xxx.com/?wordfence_syncAttackData=1479792976.1423
Type: Normal request
Referrer: https://xxx.com/?wordfence_syncAttackData=1479792976.1423
Full Browser ID: WordPress/4.6.1; https://xxx.com
Location: Singapore Singapore, Singapore
Time: 1 mins ago -- Tue, 22 Nov 16 05:36:15 +0000 -- 1479792975.927400 in Unixtime
Secs since last hit: 0.5753
URL: https://xxx.com/?wordfence_syncAttackData=1479792975.9166
Type: Normal request
Referrer: https://xxx.com/?wordfence_syncAttackData=1479792975.9166
Full Browser ID: WordPress/4.6.1; https://xxx.com
Location: Singapore Singapore, Singapore
Time: 1 mins ago -- Tue, 22 Nov 16 05:36:15 +0000 -- 1479792975.352100 in Unixtime
Secs since last hit: 89.9804
URL: https://xxx.com/?wordfence_syncAttackData=1479792975.2825
Type: Normal request
Referrer: https://xxx.com/?wordfence_syncAttackData=1479792975.2825
Full Browser ID: WordPress/4.6.1; https://xxx.com
Location: Singapore Singapore, Singapore
with latest version on WP and Wordfence. I am not using any proxy and it just suddenly appear rapidly since last 2 weeks. Any idea why it keeps requesting itself?