Compressed File Issue - Missing Files When Downloaded

Hello, is there a way to resolve this issue it has been a complete nightmare.

If I compress a folder containing 1 image, 1 illustrator file, 1 PSD and 1 pdf and send it via wetransfer or whatsapp - many times it will just randomly skip one file. So instead of 4 items the person downloading it, will only receive 3. Sometimes the entire folder is empty. However when I download it again, I can see everything.

What am I missing? Please help!