I have the exact same problem my man. Sent from Bitcoin Core wallet to Coinbase on the 12th of december. Been pending ever since on Coinbase, with no confirmations.
The transaction ID shows something else though, it says its been received 9 days ago and 4 hours ago, which is weird. I also found the Child transaction to be hard to grasp.
Since this is the same issue, ill just post my transactions here too. Hope someone can help out.
TX-ID
8cf13c3a51c9ae898b0950bab9e077891b59840831d13a2e411d8ed0e44918a6
16ec484870fdc320e49b56035e1a625f447c4490606e3a7749ba3919744dff9c