Just a suspect because I do not know the internals of easyform, but maybe mayler is just a default value not bound to any object and thus modifying it will not trigger a write in the ZODB.
I have already seen this issue in dx schemas.
Let's say you have a field 'people' Choice(..., default=), whenever you do:
you will trigger no write in the ZODB is obj.people in not yet an attribute of obj and if you do not set obj._p_changed=1.
Hope that this can help.