We have done a lot of tests on the DJI Mini 3 Pro. Here are some findings.

• DJI's Charging Dock states that it supports power input 5V==3A,9V==3A, and 12V==3A, but our power bank cannot support 12V==3A. So the DJI charging dock will negotiate the power input with our power bank at 9V.
• But when we connect the DJI charging dock to our power bank, we find that the dock only asks for 9V==2A at the first, so our power bank only gives 9V==2A. That's why you will find the real output hovers around 18W. But sometimes the dock doesn't comply with the agreement, it asked for 9V==2A first but then compulsively drew 3A from our device, thus the voltage our device can finally give will be lower than 9V (because the total needs our power bank received at the very first is 9V==2A=18W, if 3A is drawn, then theoretically the final voltage will be 18W/3A=6V). Therefore, the UVP Low voltage warning will appear.
• We also test the charging dock with some of our 9V==3A chargers (who also do not support 12V), and the testing results are also the same. So it seems that the charging dock's charging ability at 9V==3A has some unknown problems. Regarding this point, maybe you can also try some 9V==3A chargers (that do not support 12V) to see whether you can get the same results as ours, or you can also have a further discussion with DJ later.
• We find that the charging dock's charging ability at 12V performs well. When it is charged with a 12V charger or power bank, there will be no charging issues. Therefore, our engineer will improve our power bank and add the charging ability at 12V in the near future, which should help to be better compatible with the DJI Mini 3 Pro.

If you need further assistance, please feel free to contact us.