I can replicate this problem - I did a brand new test project on the humanitarian server, it only has 4 questions, one question asks the user to upload an attachment.
I have submitted the form 10 times, swapping between 3 different pdfs and a text file, sometimes with long names and sometimes same file with a different name (as initially I wondered if the . in the filename or else the longer filenames were causing the issue). File sizes range from 1KB to 7,500KB.
Of the 10 submissions, only two work succesfully - eight get the error above (Could not retrieve <filename> ) when I go into the view modal, and also get an error when going into the “edit” view (File <filename> could not be found (leave unchanged if already submitted and you want to preserve it).)
However, all files are present if I do a media download (noting that I get a “the Compressed (zip) folder <filename> is invalid” error when opening using normal windows tools, have to use 7-Zip to unzip the downloaded zip folder - not sure if that’s related at all)
I can’t pin down what is different about my different submissions - @Kal_Lam please feel free to take a look at the project if it helps your troubleshooting: https://kobo.humanitarianresponse.info/#/forms/ahMRgiCEFX3hvh5cerSa6x/data/table
Thanks
