DP006 you say? Supposedly same (problem) "feature" as with my DP008. After several testing I understood the following:
a) ensure the ASSIGN configuration for input A+B points to the correct tracks
b) arm both tracks for recording - PAN controllers do nothing during recording
c) PAN controllers have to be used within BOUNCE/MIXDOWN.
But keep in mind different behavior for mono (one) or stereo (two) track recordings!
c.1) pre-recorded mono tracks can be kept in C for the mixdown
c.2) pre-recorded stereo tracks must be panned L and R to achieve a stereo image. If you keep both on C you will just get a muddy mono-ish sound in front of you, no stereo image.
This is my experience.
Curious if it works also for you.