All you can do is wait for the understaffed IRS to process your return ... mailed in returns are taking 6 months or more this year so patience will be needed ... check the IRS site once a week until you see some progress :
https://www.irs.gov/refunds
And the advance CTC payments will not be issued until the 2020 return is processed but if you don't get them in advance then you can apply for the credit on the 2021 return.
Now going forward ... know the rules....
There is no such thing in the Federal tax law as 50/50, split, or joint custody. The IRS only recognizes physical custody (which parent the child lived with the greater part, but over half, of the tax year. That parent is the custodial parent; the other parent is the noncustodial parent.)
Who can claim the exemption and credits depends on who is the custodial parent. (By the IRS definition of custodial parent for tax purposes - this is not the same as the legal custody that a court might grant.).
The test that the IRS uses to determine the custodial parent is where the child lived for more than 1/2 (or greater part) of the year. The IRS will go so far as to require counting the nights spend in each household - that person is the custodial parent for tax purposes (if exactly equal and more than 183 days - The custodial parent is the parent with the highest AGI, if less than 183 days then neither parent has custody so the child cannot be claimed by either parent). And yes they are that picky.
See Custodial parent and noncustodial parent under the residency test in Pub 17
https://www.irs.gov/publications/p17#en_US_2017_publink1000170899
Only the Custodial parent can claim: (Child would be listed as non-dependent EIC & CC only)
-Head of Household
-Earned Income Credit
-Child Care Credit
The non custodial parent can only claim: (Child would be listed as dependent)
-The Exemption
-The Child Tax Credit
But only if specifically specified in a pre-2009 divorce decree, separation agreement or the custodial spouse releases the exemption with a signed 8332 form - after 2009 the IRS only accepts a signed 8332 form that must be attached to the non-custodial parents tax return.
