I am also having this issues of unable to purchase books from a bookcase in live mode. I have not found an answer to this issue yet. I have tried a completely new save, and a new sim, and still have the issue. the only think I downloaded were the free kits (country kitchen & Holiday)
I'm having the same issue and I also downloaded the free kits. I was able to fix it by deleting the Sims 4 folder under Electronics Arts in My Documents with several attempts. After deleting the folder on my 1st try, there was a new bug where the Purchase Books option was missing from the Bookcase menu. Same with the Order menu, it is also missing from the computer. After several attempts of deleting the Sims 4 folder and validating the installed files (through Steam), I was able to purchase new books. Although, after a few hours of playing the original issue of not being able to buy new books happened again. I hope EA rolls out a patch to fix this issue.
