I'm having the same issue!
I followed the steps to download the TurboTax desktop app for Mac, manually calculating the credit, and manually adding the credit to Form 1040 for the Federal Return.
But when trying to add the credit to Form 540 for California, I'm unable to edit the cell/box and add the value. This would prevent me from getting the proper tax credit for the state return which is unfortunate. Very frustrating after all this work.
