If TwinDos is not using detergent, check that the function is selected, that the program supports it, and that each cartridge is in its correct compartment.
Selected function and compatible program
The manufacturer documentation notes that TwinDos is not available in certain programs, such as Silk or Wool on the described machines. Check the table for your model: not using product in a program that does not use TwinDos does not prove a fault.
Before the next wash, check whether automatic dosing is active and whether the corresponding cartridges are inserted correctly. Do not also add a full manual dose to compensate for a suspicion that has not been verified by checking the selection.
Set amount and maintenance
Compare the settings with the reference on the packaging and the water hardness and soil level conditions. Note which cartridge stops being used and during which programs, instead of repeating washes without changing any conditions.
If a care reminder appears or there has been a long period of inactivity, consult TwinDos maintenance. Do not disassemble pumps or add cleaning products outside the system procedure.
If the function is configured correctly, the program supports it, and consumption does not resume, request service. An unrecognized cartridge and a recognized cartridge that does not dispense are different issues.
Report the program and the affected cartridge; they help distinguish a usage selection from a dispensing problem.