Money disappeared due to "no memo"

My wife transferred some USD from a coinbase wallet to her account about a week and a half ago. Yesterday, the transaction history disappeared, and the money still hasn't shown up.

Luckily she took screenshots of the transaction as it was happening.

After 2 hours on the phone with coinbase, they said that because she didn't include a memo with the transaction, it "dissappeared."

Is this normal? It seems extremely sketchy to us.