My son has a disability and I get to transfer his credits to my taxes and last year that transfer was $6431 and this year it's showing zero what's wrong there

Ensure that all the required information has been entered. Along with the Dependants section in the Setting Up stage of your return, there's another required section in the Deductions (Additional Dependant information).

If the issue persists after completing all of the required information, please contact our phone support team for further assistance.

https://turbotax.community.intuit.ca/replies/3152013