As it seems on Check Point R77.30 Take_351, it is possible that after adding a new VLAN interface a it may fail to route traffic. When looking at the cluster status, everything seems OK. But when you take a look at the routing table you notice that actually the newly added network is missing.
Doing the usual “cpstop & cpstart” does not fix the issue. What actually was needed to get it to forward traffic to the good old “have you tried turning it off and on again”. If it happens on your primary cluster node just fail over to the secondary node and reboot.