Testing on my own device with a fresh install of version 3.22 and after deleting all the persistent data (found in CoquetteDragoon-3.22-pc\game\saves and C:\Users\[your username]\AppData\Roaming\RenPy\CoquetteDragoon-1597701435 ) the next chapter was unlocked at the end of chapter one, and also was able to read by using the unlock function... I'm not sure what's causing the issue on your device, I've made sure it saves the persistent data after changing the variable for unlocking the next chapter. In any case, try deleting everything at these two locations, opening the game and pressing unlock and the chapters should be readable.