Does the issue occur on DVDs as well, or only on Blu-rays (assuming you own the dvd ripping portion of DVDfab)
You are correct about the missing details being a problem. At the end of conversion, you should get Title, Video Length, Video Frame width, Video Frame height, Video Data rate, Vudeo Total bitrate, Video Frame Rate, Audio Bit rate, Audio Channels, and Audio Sample Rate. The remaining fields will be blank.
Logan ripped fine for me using 10.0.5.9 (x64) using H265 MKV and hardware encoding (GTX 1050) - The 980 does support H265 I believe, so it should be using hardware encoding for the conversion, but the actual finalizing of the file would be done by DVDFab and would be where those details are processed. To clarify, DVDFab says the process completed successfully, but the file is missing the data?
Your logs are from 8/31. I assume that the updates since then (current version as of now is 10.0.6.2) didn't fix this for you? You're running the latest drivers for your graphics card?
The next place I'd look is your antivirus. If it's somehow blocking DVDfab from writing the final output to the file with the file details (and somehow DVDfab thinks it's working when it's not) that could be the cause. Try disabling your antivirus and see if the issue persists. Lastly, try going to Copy>Main Movie and rip the main movie to an ISO file. Then try converting the ISO to an MP4 and see if that works. That'll tell us if it's specific to ripping from disc straight to MP4 or if it applies to all blu-ray sources.