The possible reasons are that the added format is not supported, the file is too large, and I forgot to save the future worry-free upload attachment. There are two save buttons to save.

The format requirements of attachments added by Worry-Free Future: GIF and JPG files are supported, and the size of each attachment is limited to 500K K, and the total amount cannot exceed 2 M..

Moreover, it should be saved once after the attachment is added, and also once when the resume exits as a whole.