Please use this thread going forward: Write Song / Book / Lyrics Loses Progress | EA Forums - 4973703
@TashaAnne77 Hello and thanks for sharing! I tested this again in an unmodded save and the problem with progress resetting is still happening for me.
You mentioned merging households. I wonder if you've been playing the one household since before the 26 July 2022 update. I'm not sure if the issue was caused by that update. It's just that I didn't notice the bug until after that. So, if you've been playing that one household for a long time, I think it's possible that the bug was introduced for you with the newer sim / household. That's just a guess though.
I doubt that a cheat code would've caused it but I don't know that for sure.
Edit: I thought I might mention that my workaround has been to use a mod by Mikya that reduces the amount of time it takes to write. We're not allowed to link mods here so, if you're interested, perhaps run a search for it. Hopefully the bug is fixed though since I try to limit the number of mods I use because of their potential to break the game. Fortunately, I have not had any problems with the Mikya fast write mod (knock on wood :-)
