pH Control upward/downward - Abnormal switching

Hello,

I have a Profilux Mini WiFi with the latest firmware (1.14).

I am experiencing something with the pH upward/downward logic that I cannot understand. Here is the issue:

pH nominal value is set to 6.30, hysteresis to 0.6. My understanding is that ph control upward should switch on when pH drops below 6.00, and pH control downward should switch on when pH is above 6.60.

The pH in the tank is currently 6.37, and there is a "-" sign on the right of the pH value, and the pH control downward is switched on (the control upward is switched off).

Few days ago, pH was 6.15 with a "+" sign displayed, control upward was switched on (control downward was switched off).


Is there anything I am missing?
Appreciate your help.

The + ore - stays until ph= 6.3 ist reached