Upgrade from 11.2.0.4 to 12.1.0.2 prevents Oracle Text Index preference small_r_row from working

I am asking this in the hope that someone else has come across the same issue and maybe there is a patch out there already for this problem.

We started experiencing row-lock contention in syncrn() on one of the Text Indexes in our app, so we attempted to follow the documented solution in 12.1.0.2 which is to enable the "small_r_row" preference and rebuild the index.

However we've found that on databases upgraded from 11.2.0.4 to 12.1.0.2, some defaults have been changed which renders this preference unusable. We proved this with a simple test script run on a fresh 12c DB vs an upgraded DB. On the fresh 12c DB we generate multiple $R rows but on the upgraded DB we only generate one $R row (the default).