OpenZeppelin onlyOwner修饰符异常：getICOMembers函数Etherscan调用失败

在Remix环境中，getICOMembers函数可正常工作，能返回添加到icoMembers映射后的指定ICO类型的所有成员：

映射定义 #

mapping(uint256 => address[]) private icoMembers;

getICOMembers函数 #

function getICOMembers(uint256 _icoType) external view onlyOwner returns (address[] memory) 
{
    return icoMembers[_icoType];
}

但使用Owner地址在Etherscan上调用该函数时，始终返回错误。而同样带有onlyOwner修饰符的getICODatas函数却能正常工作：

ICOdatas数组定义 #

ICOdata[] private ICOdatas;

getICODatas函数 #

function getICODatas() external view onlyOwner returns (ICOdata[] memory) 
{
    return ICOdatas; 
}

已尝试以下操作但问题未解决：

• 硬编码添加成员（不通过代币销售加入函数）
• 将函数的external修饰符改为public

以下是合约的构造函数代码：

constructor(
    address _token,
    address payable _usdtWallet,
    address _vestingContract
) {
    require(
        address(_token) != address(0),
        "ERROR at Crowdsale constructor: Token contract address shouldn't be zero address."
    );
    require(
        _usdtWallet != address(0),
        "ERROR at Crowdsale constructor: USDT wallet address shouldn't be zero address."
    );
    require(
        _vestingContract != address(0),
        "ERROR at Crowdsale constructor: Vesting contract address shouldn't be zero address."
    );

    token = ERC20(_token);
    usdtWallet = _usdtWallet;
    totalAllocation = 0;
    vestingContract = IVesting(_vestingContract);
    transferOwnership(msg.sender);
}

内容的提问来源于stack exchange，提问作者samet mollaoglu