You quite clearly stated the normal 'OFF' flag appears when a "reversed sensing condition" is detected, now you're saying its the respective (ADF) fail flag....?
Yes, the normal flag when the respective ADF receiver either fails, or the 180 degree ambiguity is sensed.
The legend on this flag is...OFF.
There are, however, different variations, depending on original customer option...in fact, those aircraft ordered by TAP had a separate RMI for the ADF indications...IE: two RMI's on each pilots instrument panel.
Many of the aircraft delivered originally to BA had a completely different ADF display...IE: the respective ADF pointers were placed on the HSI...which caused this instrument to look like, as one pilot described it...a pin ball machine.
And, yes, I've flown this varient as well, complete with its 'ground pointer' on the ADI.