Tucson TLE – Problems with exhaust gas cleaning system

Hello Tucson friends, we have problems with our new Tucson Diesel 2.0l/185 PS Automatic approved at the end of January. At about 5,700 km the DPF fault light lit up. After a restart it stayed out at first, but after a few kilometers again light up, this time together with the “MIL” warning light. From the side of the workshop the DPF filter was burned out and the system reset. Approximately 1 week later the DPF fault light lit up again. At the restart in the evening it stayed on I then drove, even longer than recommended in the operating instructions, about 50 minutes on the expressway with changing speeds (approx. 100km/h), in the 4th gear or higher and with approx. 2000 rpm. The DPF fault lamp stayed out. But only for approx. 1 week. Then it lit again and shortly afterwards also again the “MIL” warning light, by the way again without any loss of performance or other indications of defects. Now the car stands for the second time again in the helpless contract workshop, the au f Instructions from Hyundai is waiting. The car has been very responsible, has now about 6,000 km on the tacho and rather disappointed owners. Has anyone experienced similar, or an idea what might be the cause? Thank you for your advice!