Cisco AAA/Identity/Nac :: Use 802.1x To Authenticate Clients On Network With Dynamic VLAN Assignment From RADIUS?

I'm trying to use 802.1x to authenticate clients on my network with dynamic VLAN assignment from RADIUS. We have IP-Phones(powered by PoE) that only supports EAP-MD5, and we would rather use MAB(it also uses LLDP-MED for some settings) to authenticate the phones using the MAC-range from the phones vendor. The following scenario works perfect:Connect the phone and let it boot up(takes a while) and authenticate with MAB.Connect a computer in the phones data-port and let it authenticate with 802.1x(or fail and reach guest-vlan) However, the following scenario doesn't work:The computer is already connected to the phoneThe phone is then connected to the switch What happends now is that the computer is authenticated using 802.1x before the phone boots up and get's authenticated with MAB. When the phone is ready, it's authenticated with MAB and everything works. However, after a short period(let's say a minute), using `debug authentication all`, we see a "NEW LL MAC: phones mac" message(which is weird since the mac has already been MAB-authenticated), and then we are unable to contact the phone using ping. When I check `show mac address-table` it has now moved the mac from `Port Gi 0/12` to `Port Drop`. However, if I check `show mab interface Gi 0/12` or `show authentication sessions` it lists the phones-mac as `mab auth sucess `.why the first scenario works, and not the second?
 
The switch is a 3560E PoE 24p with IOS 12.2.58SE2. Sample of the switch-config: network-policy profile 1voice vlan 90!interface GigabitEthernet0/12switchport mode accessnetwork-policy 1authentication control-direction inauthentication event fail retry 1 action authorize vlan 60authentication event server dead action authorize vlan 60authentication event no-response action authorize vlan 60authentication event server alive action reinitializeauthentication host-mode multi-domainauthentication order mab dot1xauthentication priority mab dot1xauthentication port-control autoauthentication periodicauthentication violation replacemabdot1x pae authenticatordot1x timeout tx-period 5dot1x max-reauth-req 1spanning-tree portfast!Btw, when we tried authenticating the phones using 802.1x too (EAP-MD5), there are NO problems in any of the scenarios. However, we want to use MAB instead of 802.1x to avoid the requirement of configuring the phones with a username and password. The RADIUS response was the same when using 802.1x as it is with MAB for the phones (including device-traffic-class=voice AV-pair).