Fix for operator enable when using only one instance.

UI.hpp

@@ -3443,6 +3443,7 @@ void UI_handle_OP(uint8_t param)
 
     if (LCDML.BT_checkUp() && encoderDir[ENC_R].Up())
     {
+#if NUM_DEXED>1
       if (op_selected == 0)
       {
         selected_instance_id = !selected_instance_id;
@@ -3450,10 +3451,12 @@ void UI_handle_OP(uint8_t param)
         lcd_OP_active_instance_number(selected_instance_id, configuration.dexed[selected_instance_id].op_enabled);
       }
       else
+#endif
         op_selected = constrain(op_selected - 1, 0, 5);
     }
     else if (LCDML.BT_checkDown() && encoderDir[ENC_R].Down())
     {
+#if NUM_DEXED>1
       if (op_selected == 5)
       {
         selected_instance_id = !selected_instance_id;
@@ -3461,6 +3464,7 @@ void UI_handle_OP(uint8_t param)
         lcd_OP_active_instance_number(selected_instance_id, configuration.dexed[selected_instance_id].op_enabled);
       }
       else
+#endif
         op_selected = constrain(op_selected + 1, 0, 5);
     }
     else if (LCDML.BT_checkEnter() && encoderDir[ENC_R].ButtonShort())