It's performing passive regens. They will not show up on your DPF gauge.
ACTIVE REGENERATION
An active regen will occur when the soot level reaches 80% and/or every 24 hours.
An active regeneration is triggered when the DPF exhaust back-pressure reaches a certain back pressure point that is interpreted as 80% soot for the Cummins 6.7. Then the ECU initiates a fuel injection designed to increase the exhaust temperature in the DPF to over 662 degrees F in order to oxidize the particulate deposits. When completed, the ECU assumes a small amount of residual soot and resets the value to 6-9%. The 2020 3500 trigger point is 80% soot. (100% on an Edge CTS3).
PASSIVE REGENERATION
A passive regeneration occurs when the load and speed of the engine produce DPF exhaust temperatures greater than 662 degrees F, and it burns off the trapped DPF soot as the vehicle operates. Generally, the EGT’s do not get hot enough for a passive regen at unloaded speeds, thus, some trucks may never or seldom see a passive regen. However, when towing, carrying a full load, or driving hard the EGT’s can reach passive temps and perform passive regenerations. (EGT3 sensor)