Once upon a time, I was writing the novel
Eternity, which is a sequel to
Wee.
In my book, Eternity is a board game played by the gods. Their board is the world, and the playing pieces are its people. In this particular game, adventurers set out from the city of Tâelè for the city of Iolo with the intention of stealing the Elixir of Immortality. Meanwhile, adventurers from the city of Iolo set out for the city of Tâelè with the intention of stealing a magic mirror containing the Great Quill, a legendary prophet. None of the adventurers realize that they're just pawns of the gods.
About 1/3 of the way through writing
Eternity, my interest waned.

I came to the conclusion my main characters were boring, and so I became bored.

Recently, I came across this video:
Ms Brock sets out 2 reasons why characters lack clear goals (thus causig boredom).
First, is when the MC is part of a group, and the MC's goals are subsumed into the group's goals.

This is what appeared to have happened with my first group, and it shouldn't have.

In my early drafts of
Wee, big dumb Elvis was the MC and van Klunk the wily gnome was his sidekick. It was only towards the end that I realized van Klunk was the interesting character an should be the MC. So I switched their positions, added a new first chapter & renamed the story
Wee. For some unknown reason, when I stated writing the sequel, they retook their original positions. So, if I switch them back, my problem is solved.

Indeed, van Kluck has just stolen the group's treasure and has abandoned them.

That's interesting.
My second group has the second problem pointed out by Ms Brock. There, my MC changes goals easily--which indicates an undiscovered, underlying goal. I've now worked one out for her, to erase the humiliations of her childhood by becoming celebrated.
I still have no idea how this book will end.

I have two distant groups of questers, two interlocked games of Eternity being played with manipulations by multiple gods, and I don't even know how to win Eternity.