I spent a while trying the Examples --> ArduinoBLE --> Central --> LedControl With 2 Nano 33 IOT's and a few Nano 33 BLE's . The Peripheral LedControl was working but the Central was having troubles.
I made several changes but when things really started working was when I made this change to line number 91
// retrieve the LED characteristic BLECharacteristic ledCharacteristic = peripheral.characteristic("19b10001-e8f2-537e-4f6c-d104768a1214");
// Note the 2 GATT's are slightly different: service=19b10010, LED=19b10011 BLECharacteristic ledCharacteristic = peripheral.service("19b10010-e8f2-537e-4f6c-d104768a1214").characteristic("19b10011-e8f2-537e-4f6c-d104768a1214"); //worked
Hope this helps someone else.