@dabuv A configuration fragment you have then added to the switch does not reveal the actual configuration, posting the exported config does.
In that fragment port 48 is also an untagged member of VLAN 1 due to pvid=1 automatically being added as the default, use ingress-filtering=yes frame-types=admit-only-vlan-tagged to make a port tagged-only
You have no communication with the CRS as the implicit bridge-to-CPU port membership has not been included in the /interface bridge vlan configuration, this http://forum.mikrotik.com/t/routeros-bridge-mysteries-explained/147832/1 is a good explanation.
The CRS3xx devices only support hardware offloading on one bridge, performance via additional bridges will be significantly less than wire-speed.
@anav the CRS3xx are the only Mikrotik devices which automatically support VLAN-aware hardware offloading, there is no separate switch VLAN configuration.