Ah, I think I found the bug.
My claimed CCA for 2023 was high. I think TurboTax opted to use the CCA against my income rather than my home/office expenses. But instead of saying $0.00 or "Already maxed/fulfilled by another category" it said 'not started'.
I found this out by reducing my claimed CCA. Afterwards the home/office expenses started to show though.
