Moodle Wiki - wiki page files disapearing (all at once)

Hello,

my classmates (including me) have been experiencing random Moodle issues when editing wiki pages. It seems that once we upload images through the wiki page editor and use them on that page they stay for a while (few hours, a day or several days - looks pretty much random) and then disappear. If I edit the wiki page after this then the respective images link to brokenfile.php - which is understandable since those are no longer in the system.

This not only happens when more people are editing the same page (where I can't prove they didn't do anything wrong) but it also happened to me when only I was editing the wiki page. One day it was there and then if I checked the page a few days later it contained no images whatsoever - and the files were empty as well. I was the only person mentioned in the changelog and since the files were gone (for good) not even reverting the page in the version history could fix the issue.

So for now the only way for us to reliably submit images to our wikipages is to use external links and hosting our images elsewhere. Saving the files to each person's repository doesn't help either - if I choose not to make a copy of it to the respective wiki file repository then it changes the url to brokenfile.php as well - making it not usable. Hardcoding the correct url in the html source editor doesn't help either as it always changes it.

Anyway, I am not sure how to reproduce this issue. It happened to several people in my class yet no one knows how since the files were present right after the last edit but were not present once someone checked the wiki later (without editing it).

I found several bug reports that may be relevant to this yet none of them seems to precisely fit the above scenario:

https://tracker.moodle.org/browse/MDL-49692

https://tracker.moodle.org/browse/MDL-50463

They both seem to be duplicates of this issue: MDL-48371 (but neither of us have permissions to access this report so we can't say whether this is a duplicate or not)

Thank you very much for looking into this. If any additional information is needed please let me know and I'll try to respond ASAP.

Steps to reproduce:

1. As a teacher create a 'Collaborative wiki' in a course with 2 students or more.
2. Student1 creates a new wiki page which and adds some files using the atto editor. And waits till the content is autosaved.
3. is autosaved, but not finalised (the autosave includes the current state of files at the time).
4. Student2 creates or edits another page (not even the same page), uploads files using atto editor, and saves the page.
5. Student2 acceses to 'Files' tab and see the files they uploaded are listed ok.
6. Student1 accesses the page, clickin on Preview button for example, to check everything is ok (including the files state), and saves the page.
7. Student2 acceses to 'Files' tab and see the files they uploaded to their page are not there anymore.