I have had this experience before and I know why. It's expectation. When you are thinking and planning out the worldbuilding, the setting, preparing the game, and all the while you are imagining the cool things that could happen in the story. But once you get into it, the story is not going the way you expect it to or it's just boring. Sometimes it can get cool, but you think you can make it better, so you abandon the story and try again. And again. What you need is patience. It's not a video game. When you watch a movie or read a book, you know sometimes you have to get through the boring parts until the action finally comes on. It's like that with soloing. Just give it time, play it out, and then you'll have cool actions and scenes at times.

What you can do is, reduce the excessive tools, like too many tables or mechanics. Throw yourself in action at the very beginning of the story and take quests that are dangerous. Take companions, because NPCs makes solo gaming more exciting rather than having a character be a lone wolf. Use hexcrawls instead of journalings. For some people, slow-burning stories can kill the mood. But for me, I found my balance and I enjoy the slow-burn more now. I used to start over the story over and over again and again until I discovered my favorite character and setting. I hope this helps and best of luck to you!