It looks like this bug has been fixed. I had been holding off transmitting my taxes because of the bug. Two days ago I went back into TurboTax, and after letting it update itself I started a fresh federal return from scratch (rather than editing the one I had been working on). After entering all of my data, including charitable donations, I looked at the return. This time the "unacceptable value" error did not happen, and the $600 value was recorded correctly on my return.
I don't know I needed to completely re-do my return from scratch. I didn't try just editing the return that I previously worked on. Perhaps it also would have worked correctly.
