"automatic sdf downloading is disabled or failed"
However , makemkv continued to process the disc, listed the titles, and even highlighted the probably main title as "FPL_MAINFEATURE".
I checked "Preferences->General" and downloading updates from the web server is enabled. What is the web server hostname? I have pi-hole and pfBlockerNG running to filter DNS requests. I can check their logs to see if they blocked it. I found requests for makemkv.com which were allowed, so we are good for that domain

Is it a serious problem that I should look at fixing? I don't know what SDF is so some context would be helpful.
Software info:
MakeMKV: 1.12.3
OS : MacOS 10.13.6
Java: 1.8.101
Moderator edit:
Note: hkdatastore.tk, which is mentioned a lot in this topic, is no longer the domain used for the hash key file.
Do not bother testing your DNS server to find it. It will not.
MakeMKV downloads the current location of the hash key file as part of its start-up.
Please read the entire topic for current information!