I am also having the same issue since the latest WordPress upgrade:
Wordfence Full Activity Log
[Apr 09 15:19:41:1397071181.553573:2:error] Scan terminated with error: Invaid response from Wordfence servers.
[Apr 09 15:19:41:1397071181.014971:2:info] Found 4 themes
[Apr 09 15:19:41:1397071181.010228:2:info] Getting theme list from WordPress
[Apr 09 15:19:41:1397071181.007826:2:info] Found 18 plugins
[Apr 09 15:19:40:1397071180.887749:2:info] Getting plugin list from WordPress
[Apr 09 15:19:40:1397071180.365827:1:info] Contacting Wordfence to initiate scan
