What are your settings for this in Setup - Settings - Advanced? Look at the following two, Show Ripper Indexes and Use Full Bus Name on Rippers. The symptoms indicate that either one of these has been changed after one of the buses was ripped, or that these settings are different for different users if working concurrently. Changes to either setting is not retrospective i.e. it doesn't modify existing signals.
I'd question why you want to show the index anyway, the net name reflects the connectivity after all.