VMware just release this KB article which is definitely one you should read if you use the VMware HA advanced option. In short: When you edit the HA advanced options they do not take effect until you re-enable HA on the cluster.
Be aware of this when implementing or troubleshooting HA it can cost you a lot of time.
I just got this issue but only on ESXi cluster. I changed the das.failuredetectiontime value on 4 cluster (1 full ESXi’s and 3 full ESX’s) and only the ESXi cluster didn’t update the value.