Changing roles and feats
Some feats are tied to specific roles (healer, tank etc.) and if you change your role along with your powers, you may lose access to those feats if they have not been completed. This is particularly important to note with style feats, which require armor that may be limited to a single role.
However, if you respec back to your previous role, the feat should become available again and will update to reflect your progress of any previously completed feats in other roles. Please make sure to relog your character before changing to any new role; this should allow you to maintain any new feats achieved for your previous role.