iPhone and iPad EQ intermittent issues by location

On both my iPhone and my iPad running OS26.1; the EQ works sometimes, but mostly not. It seems strange. on my iPhone or iPad at work the EQ does not work no matter what I do. At home and at the gym it seems to work fine most of the time (sometimes doesn't). It does not mater what Bluetooth eyephones I use either (iPod Pro 2 or Beats Studio Pro).Does anyone have a clue as to why this is happening?