Re: "Imessage pdfs are disappearing." " ... I am constantly sending pdfs to clients and subcontractors but now they just disappear within a day. How can I fix this issue?"
Am no expert in this area, yet your post to the community deserves some response.
If you haven't already: there are places you can check to see if the files are there.
(There may or may not be a setting in place that determines where the.pdf files are stored.
Eg: Attached Photos may be "shared" to or sent from the Photos app.)
✽ Apple support's article: Use Messages on your iPhone or iPad - Apple Support
Eg: says:
"Find attachments from a conversation
- Open the message.
- Tap the name of the contact at the top of the message."
3."You’ll see Photos, Links, Documents and more.
Touch and hold an image or attachment to show options, such as Save, Copy, Share and Delete."
Find out more about search in Messages
✽ You can search for iMessage attachments:
See: Search in Messages on iPhone - Apple Support
Eg: says:
"You can search for text messages and attachments, using different criteria to narrow your results".
The above linked article gives "how to" suggestions.
✽ Wondering if the original PDF's you attached are in the Files app or the Books app.
or if the pdf attachments may be showing up there.
Searching for a file name there may help uncover them all:
Eg: Read PDF documents in the Books app on iPhone - Apple Support
✽ You can check "Recently Deleted" to see if missing pdf's have accidentally ended up there.
See how to: Recover deleted messages in Messages on iPhone - Apple Support
✽ If you use iCloud: perhaps the missing attachments show up there ? Eg: https://www.icloud.com