Having the same issue I constructed a erc20 contract on remix. I was able to verify on kovan.etherscan without arguments but when I try on etherscan it’s give error invalid constructor argument provided. Please verify that they are in abi encoded format.
I tried the hashex but didn’t know what parameters to enter.
The contract address is 0xEB9ef47a5f4b4840948C4ef4967B49993d7202Fb