Greg brought to my attention that HP Tuners does not yet support the Transmission Current Gear pids for at least one of the latest ECMs, so I updated the app to handle this scenario. But instead of just ignoring the transmission gear, I implemented an approach that automatically identifies the current gear based on the ratio of the vehicle speed to the engine rpm.
It uses kernel density estimation on the ratios to assign a transmission gear. The attached graph is an example from a real log. Think of the density estimate as a continuous version of a histogram. This log contained the most 4th gear data since its peak is the highest, and the least 6th gear data since its peak is lowest. The vertical blue dotted lines mark the ratio values identified as a transmission gear peak, and the horizontal red dashed line is an adaptive floor value, below which any peaks are ignored. Each datalog record is then assigned to the transmission gear whose ratio is closest to it. There is spread around the peaks because tire rolling diameter and traction are not fixed values, plus transitions occur during gear shifts.