F5 LTM VIP/STP Problem

we're seeing a similar issue here. it's random and often traffic will flow one way but not the other and some virtual server ip's will be reachable but others will not. On the host the IP will have the correct MAC in the ARP table on the host but traffic will not pass. So far all but one have been corrected by changing the teaming type to NFT from automatic. I was chalking it up to extensive use of Route Domains on our end but it sounds like a larger issue?