I have been running the public beta of MacOS Mojave for some time now trying to see how all my current apps and workflows may or may not be affected.
I have been quite pleased that DxO PhotoLab has been working quite well with just two cosmetic issues.
In High Sierra, the Presets window contains text that is white and assume normal type. In Mojave, the text appears black and seemingly as boldface. Against the standard gray background it is difficult to see. When an item in the presets is selected the text does turn white.
A similar situation occurs with drop down menus which is the only other issue I have encountered.
Other than these issues, performance seem the same as with High Sierra and all functionality including exporting, tools, etc. all seem to be without issue.
I am guessing you are testing with the developers beta (well, should be) and not sure if you encountered this but thought I would bring it to your attention.