FYI, from Klipsch.
Thanks for contacting Klipsch!
They may have dynamic bass mode enabled. The update added bass cut mode which is listed as night mode in the Klipsch Connect app so it matches our other products with night mode. They should be able to hold down the sub reset button and see the LED on the top of the active speaker flash 1-3 times depending on what mode it's in.
1 flash = Dynamic Bass mode
2 flashes = Flat mode (Default mode)
3 flashes = Bass cut mode
This could be the case that many folks are reporting, and not noticing which mode the speakers are set in.
Also, it is true that the firmware is not able to be rolled back.