I had a similar issue with DxO Pr3. I found the issue was related to how the LrC plugins were handled during an update. I uninstalled Pr3 and also deleted the plugins from LrC. I then reinstalled Pr3 and it seemed to work fine. I found that just uninstalling Pr3 would not remove the plugins from LrC.
I am very disappointed with DxO support! I have an issue where the application will stop processing images in LrC on my computer, the only way I can get it to work again is to exit out or LrC and restart. I have submitted a number of files, videos, and configuration reports to DxO with no resolution. In fact there is no communication unless I initiate it. I have been working on this since March and I am getting nowhere. I have asked if they can just refund my purchase and they repeatedly deny that request saying they need time to research the problem, problem is they won't give me any idea how long they might need. Very frustrating, I install each new update, test it, it fails after 1 or 2 images and I update my support request.