"Virtual" keyword makes any function non returnable - help

[JayeshShukla]

run the below code in remix or any of your favourite compiler and be stunned to not see any output but a receipt.
then remove the "virtual" keyword and BOOM you see the output. - PLEASE EXPLAIN.

// SPDX-License-Identifier: MIT
pragma solidity ^0.8.0;

contract PrintsBool {
    function approve() public virtual returns (bool) {
        return true;
    }
}