Assuming repetier firmware in extruder.cpp function void TemperatureController::updateCurrentTemperature() at the end the temperatur is corrected.
#if ENABLED(TEMP_GAIN)
currentTemperatureC = currentTemperatureC * tempGain + tempBias;
#endif
So if it is always 0 you have tempGain and tempBias for that heater 0.
There is no mean to set it for bed. In eeprom.cpp in void EEPROM::restoreEEPROMSettingsFromConfiguration() you have the initalization in case you reset it from config:
#if ENABLED(TEMP_GAIN)
heatedBedController.tempGain = 1.0;
heatedBedController.tempBias = 0.0;
#endif
But you should also see it in eeprom due to this:
#if ENABLED(TEMP_GAIN)
writeFloat(EPR_HEATED_BED_GAIN, PSTR("Bed Temp. Gain"), 4);
writeFloat(EPR_HEATED_BED_BIAS, PSTR("Bed Temp. Bias [degC]"), 4);
#endif
