音频文件多次上传无法在php中使用

Question

我在下面创建了PHP表单，用于将mp3文件发送到数据库。

<form action="" method="post" id="audioForm" enctype="multipart/form-data">
    <div class="form-group">
        <div class="row audiosRow">
            <div class="col s12">
                <div class="file-field input-field">
                    <div class="btn btn-small">
                        <span>Track</span>
                        <input type="file" name="file-1">
                    </div>
                    <div class="file-path-wrapper">
                        <input class="file-path validate" type="text" placeholder="Upload audio files* (.mp3)" readonly="">
                    </div>
                </div>
            </div>
            <div class="col s12">
                <div class="file-field input-field">
                    <div class="btn btn-small">
                        <span>Track</span>
                        <input type="file" name="file-2">
                    </div>
                    <div class="file-path-wrapper">
                        <input class="file-path validate" type="text" placeholder="Upload audio files* (.mp3)" readonly="">
                    </div>
                </div>
            </div>
            <div class="col s12">
                <div class="file-field input-field">
                    <div class="btn btn-small">
                        <span>Track</span>
                        <input type="file" name="file-3">
                    </div>
                    <div class="file-path-wrapper">
                        <input class="file-path validate" type="text" placeholder="Upload audio files* (.mp3)" readonly="">
                    </div>
                </div>
            </div>
            <div class="col s12">
                <div class="file-field input-field">
                    <div class="btn btn-small">
                        <span>Track</span>
                        <input type="file" name="file-4">
                    </div>
                    <div class="file-path-wrapper">
                        <input class="file-path validate" type="text" placeholder="Upload audio files* (.mp3)" readonly="">
                    </div>
                </div>
            </div>
            <div class="col s12">
                <div class="file-field input-field">
                    <div class="btn btn-small">
                        <span>Track</span>
                        <input type="file" name="file-5">
                    </div>
                    <div class="file-path-wrapper">
                        <input class="file-path validate" type="text" placeholder="Upload audio files* (.mp3)" readonly="">
                    </div>
                </div>
            </div>
            <div class="col s12">
                <button class="btn btn-small" type="submit" name="submit">Save</button>
            </div>
        </div>
    </div>
</form>

当我发送图像时，该表单工作正常，但是当我发送音频文件时，该表单不能用于三个或三个以上。当我制作一个var_dump($_FILES)时，它显示array(0){}。

所以我认为这可能是一个限制，但我在任何地方都看不到。我检查了php.ini配置文件，我有upload_max_filesize = 200M和max_file_uploads = 20。

那么问题出在哪里？请帮助我。