I am having this issue with multiple apps. I am creating a record on a custom SP list. the list is simple with one text field and then the attachment. The user uses the attachments control within a form within a powerapps canvas app to take a photo with eir mobile device and then once the photo is captured the user clics button to submit form. An attachment is required.
On a successful submission the record is created but it appears that intermittantly the attachment gets lost along the way and i get a sharepoint record with no attachment.