Questbook Not Opening

So I've had this problem where recently I'm unable to open up my quest book and even if I did, it would say, "Invalid Book Tag". I tried relogging back and I tried /class but it doesn't work (for some reason when I start a new profile the quest book works again). I've also switched versions to 1.12.2, the recommended version and still doesn't work. I also noticed every other person who's reported this problem on either Reddit or the Forums is a new player like myself so I'm starting to feel there's a connection here.

 

This may not sound too helpful, but if you are a new player and starting another character fixes this issue, then you might as well start a new character and play as that character.