I think it can be a bad syntax here, you dont need to send those arguments as an object {}
, instead just send it normally as 2 arguments.
This is mine:
kovan: {
provider: () => {
return new HDWalletProvider(mnemonic, url)
},
network_id: '42',
skipDryRun: true
},
try that one in your truffle config, also if still not working, maybe it could be because you are using a seed phrase instead the hexadecimal private key (thats why your is a string of characters, while mine is a bunch of numbers and letters), the difference is that your seed contain 20 accounts with their own priv key (in hexa, like mine), so im just sending it the priv key of 1 of my 20 accounts.
Let me know how your going
Carlos Z