RV sources disappear when I add new

This is what we’re experiencing:
-we add source/multiple sources/whole playlist from Shotgun to RV
-play sources in RV
-click back to Shotgun (leaving RV window open) and add new source/s
-new sources appear but old sources are gone

We used to be able to add new sources and the old sources would still be there. We can’t figure out what changed or how to change it back. Is anyone else having this problem?