We have two kids, last year we were able to file form 8829 and get a credit for child care expenses. This year turbo tax says "it turns out you don't qualify." Why not?

The child and dependent care credit goes on Form 2441.   If you paid someone to take care of your children under the age of 13 so you could work you can enter your W-2 income or self-employment income and then enter information for the childcare credit.

Federal>Deductions and Credits>You and Your Family>Child and Dependent Care Credit

https://ttlc.intuit.com/turbotax-support/en-us/help-article/taxation/child-dependent-care-credit/L8h8A5Klg_US_en_US?uid=m5yifys1

https://turbotax.intuit.com/tax-tips/family/the-ins-and-outs-of-the-child-and-dependent-care-tax-credit/L2H7rzUWc

https://www.irs.gov/help/ita/am-i-eligible-to-claim-the-child-and-dependent-care-credit

There are certain qualifications that you must meet to be eligible for this credit. make sure that you meet the requirements:

• Must have earned  earned income (If you are Married Filing Jointly there are exceptions)
• You must have paid for caregiving expenses to work or look for work
• The care you paid for was for a qualifying person
• You aren't using the Married Filing Separately Filing Status
• You provide the caregiver's name, address, Social Security, or taxpayer ID number
• You must owe income taxes.

You can view your tax summary in TurboTax to check if you have a tax liability.  If it's zero, you won't get the Child and Dependent Care Credit:

1. Open TurboTax
2. Select Tax Tools ‌ side of the screen select Tools 
3. Select View Tax Summary. Check to see if there's a zero for Total Tax.

Review the TurboTax articles What's the Child and Dependent Care Credit?, The Ins and Outs of the Child and Dependent Care Credit, and Filing Tax Form 2441: Child and Dependent Care Expenses