The Big Brother-esque reality show opened its doors to 4.2m (1.6) in the 10pm hour.
The Glass House lost out to a repeat of Big Bang Theory (6.6m/1.8), and had less viewers than Two and a Half Men (4.9m/1.4).
The Alphabet Network's two-hour broadcast of The Bachelorette pulled in 6.9m (2.3) from 9pm, solid week-on-week.
America's Got Talent was the most-watched and best-rated show of the night with 11.2m (2.8) in the 8pm hour.
But due to a substandard performance from American Ninja Warrior (5.8m/2.0) between 9pm and 11pm, NBC ended up in second place in primetime.
Gordon Ramsay's Hell's Kitchen (5.6m/2.2) and MasterChef (5.5m/2.3) combination gave Fox a slender victory, despite both being down significantly on last Monday (June 11).