Adding ordered="true" in existing many-to-many relation

We would like to add 'ordering' to an existing many-to-many relationship. so we added ordered="true" and did a platform update, and it did not work (we cannot order the items from HMC). On the logs, we see Ordering disabled for 'relation.ourType.source.ordered' message

Here is the relation definition:

         <deployment table="From2Rel" typecode="10001"/>
         <sourceElement qualifier="from" type="From" cardinality="many" collectiontype="list" **ordered="true"**>
             <modifiers read="true" write="true" search="true" optional="true" />
         </sourceElement>
         <targetElement qualifier="to" type="To" cardinality="many">
             <modifiers read="true" write="true" search="true" optional="true" />
         </targetElement>
     </relation>

On introspecting the table, I do see RSequenceNumber and SequenceNumber columns in the relation table (this was there even before adding ordered=true). The hmc.xml also has the appropriate editor defined :

Yet, the ordering in HMC does not work with the same error message Order disabled for .....

Any suggestions are appreciated.