Intermittent issues with files not attaching to the form

Dear Support,

We have been experiencing issues with attachments. When customers attach files to our form (https://www.screencast.com/t/nplre2JBU

Thank you!

We would like to apologize for any inconvenience this is causing you, but please allow us to help you get the issue you're having resolved.

I see that the form embedded on the website already has submissions, does the issue suddenly happened or did you make any changes in the form that may have caused the issue? 

Does the issue happen on the form even when not embedded? Or, submitting the form in stand-alone (not embedded) works just fine?

How did you find out about the issue? Does it give any warning or error message when you upload the file or submit the form? If it does, may we know or can you provide us a screenshot of the error, please?

I also understand that base on the description and screenshot you provided, some of the files uploads just fine but some does not. It would really be helpful if you can send us a copy of those particular files that you're having issues uploading to your form. You can upload it to any file hosting service online, make it public, and share the link to us in this thread.

We will wait for your response.

Thank you.