I had this issue since about 2016......I hate DC offset values in ProjectPage so I've spent a lot of time to try and try to understand why this happen. I'm not a professional guy so I can only contribute saying that I have encountered several cases (I think my mistakes) that originate this:
1) appropriate gain staging that means that often I did too much encrease of the original signal in the channel strip in particular without paying enough attention to compressors
2) wrong EQ that generate frequency phase problems. For this issue, I usually mixdown one bus at a time, so I can identify in what group I have this problem. After identification I usually cut all unusefull low frequencies depending of the instrument
3) DC stationary rumble in the sub frequencies. For this issue I put a HPF in the MainOut Q48 about at 40Hz. This HPF, combined with the operations at point (2) often it is enough to solve DC problem in the loudness analysis in the Project Page.
NB: I use Project Page only to analyze loudness values (and DC) and I don't use the Project Page to master the mix or other operations.
If the step 3 doesn't work, sometimes I disable all EQ only to see if some EQ generate some unespected phase problem.
This is my way to operate, and I know that some professional guy could have the solution to save time. . Unfortunately nothing is written in the documentation and nothing you can find in tutorials about this from Presonus.
I tried to speak about this with some Presonus guru but they find fairly normal to have values in DC offset.
Pls excuse my poor english.