I thought I would post this as I figured out how to fix this issue when I was ready to quit my world and make a new one.
What you might see when you open your Better Quests book is an empty book. Restarting, the game, the machine; reinstalling, don't work. In your world your book is blank or is in some odd sort of programming mode.
This occurs when the local client engine exits while the QuestDatabase.json file has not be written to yet and closed correctly.
Upon examination of this directory .technic\modpacks\mcnewhorizons\saves\[save name] you will find that your QuestDatabase.json file is gone and is replaced by the file malformed_QuestDatabase.json0.json.
To fix this you need to create a new save, and from that save copy over a new copy of QuestDatabase.json in to your world's save directory.
In my case I created a game called, "new world" so I copied:
and deleted malformed_QuestDatabase.json0.json
And we're good to go.
Don't delete this file by accident, FYI, this is your quest progress: QuestProgress.json
Good luck friends