The Aries firmware automatically checks for smart encoders (Q-encoders) before other feedback types. If a Q-encoder is detected, the downloaded configuration on the drive will be erased.
Memory also clears when encoder signals are detected but no halls. This could occur if the halls are incorrectly wired, or not detected due to noise.
To prevent the memory from being cleared in a noisy enviroment with poor hall signals, set SFB2. This will set the feedback device to look for a standard encoder and not a smart encoder.