sendTransaction() sometimes returns a transaction hash that is not in the blockchain

[bcgreijnlautier]

I'm using an ERC20 contract to send Polygon transactions. This is a very rare occurrence, but occasionally Web3Client.sendTransaction() will return a transaction hash that cannot be found on the blockchain. I verified that the Polygon wallet did not actually send the funds. It seems that a transaction was created but was not successful, yet not error is thrown.