There are two reasons that a transaction may not appear in a receiving wallet:
Memo is careful not to display transactions unless they have been successfully broadcast to the network. Other than very rare occasions, if a transaction is visible on Memo, then you can assume it was successful.
Receiving bitcoin is a passive activity that does not require any action by the receiver. If the receiving application does not display the transaction it is not mean it is because it was not received. Most likely the receiving application has an issue or delay in reading transactions from the blockchain.
Memo cannot control the receiving wallet. If you successfully sent tokens or satoshis from Memo but they are not showing up in your receiving wallet, you will need to contact people associated with the receiving wallet, it is out of Memo's hands.