There is an issue on export in 5.2.1. This is from another thread:
We have identified a bug in certain situations affecting specifically version 5.2.1. We are preparing a fix that will be released soon.
If your processings are showing that issue, you can temporarily revert to version 5.2.0 (https://download-center.dxo.com/PhotoLab/Archive/v5.2.0/Mac/5.2.0.56/DxO_PhotoLab_5.2.x-dev_56_notarized.dmg ) until version 5.2.2 is out.
Thanks for the report and sorry for the inconvenience.