Put in Serial.print statements to see what the functions readStringFromEEPROM and scanUUID, etc. are doing internally.
For example in scanUUID:
if (newData) {
Serial.print("scanUUID: "); //debug
Serial.println(uuid);
FeederUUID = String(uuid);
In readStringFromEEPROM:
int len = EEPROM.read(addrOffset);
Serial.print("EEPROM returned len ");
Serial.println(len);