I have found a very weird issue. I had two million sil when I went to invest in the candy business, but then the old woman said the price was 7 million, just like it was supposed to be in older versions of the game. (I am using version 0.40.5, so there's no problem with that.) So I couldn't invest.
Even weirder was that, after editing the save file to have enough money and investing, I found out it had only taken away 1.4 million, just like the price was supposed to be. I have no idea what may have caused this, but it seems like I got the version of the investing event where she wants 7 million, but the payment event was the normal one.
On another note. People have mentioned a difficulty spike in the game, and I agree with that, but it is nothing compared to the spike in difficulty that can happen in the daily quests. I was going through every reclearable dungeon every day to maximize my experience, so I was at a pretty high level before getting through many "introductory" quests, and when the daily quests shifted to being about ghosts... It was ridiculous.
The ghosts were tanky enough to last a bit, which made them absolutely terrifying when combined with their powerful attacks. The wisps had multi-target fire attacks and the puppets had multi-target physical attacks. Those guys were so dangerous I was only able to win by using potions of resist fire and double barkskin potions for every battle, and even then it was a struggle.
I also used heretical censure, but when it didn't work, I was in for a bad time. Maybe it would have been easier with Kyrie, but I didn't have her in my party (I wasn't even a journeyman yet). It really made me appreciate using buffing items outside of battle, but man was it a thing.
Edit: Mostly, I was concerned because none of the other daily quests were even close in difficulty to that.