An entity had an interest in an associate. In 2010, the entity gained joint control of the associate (i.e. the associate became a jointly controlled entity). In accordance with IAS 28 (2012), the entity re-measured the retained interest to fair value. The entity subsequently accounted for its investment in the jointly controlled entity using proportionate consolidation.
The entity adopts IFRS 11 in 2013 and still has joint control; the arrangement is determined to be a joint venture. IFRS 11 and IAS 28 do not permit use of proportionate consolidation, and would seem to require the entity to aggregate the amounts recognised as of 1 January 2012. However, IAS 28 would appear to require that the entity undo the effects of the remeasurement that was recognised in 2010. Thus, the two appear to be in conflict with each other.
It would appear that an entity has an accounting policy choice, since there is a conflict in the transition provisions of IFRS 11 and IAS 28.