Hello.
The filter is on by default for L3 only (since IOS XE 3.5). You may disable it by "no otv filter-fhrp" command. More details - http://www.cisco.com/c/en/us/td/docs/ios-xml/ios/wan/command/wan-cr-book/wan-m1.html#wp3953249580
At the same time if you want to isolate your FHRP between datacenters you must configure L2 ACL (to drop FHRP MACs) and apply it inbound on LAN-facing service instances.