Subtitle text only goes away if you turn it off (gone when turned back on). The subtitle is from a side quest to pick up a vehicle from the land mine field for fixer: Dakota. It happens when you loot the body next to it. I've tried hitting pause, save/ loading, restarting the game, doing another mission, (new texts just appear underneath unless turned it off).

Edit: After over an hour later. It came back after a reload after further progress. VO and all.