How long are attachments/photos kept for?

Hello

I have not been able to find an answer to this anywhere, but how long do attachments and photos remain available on Kobo Toolbox? I have noticed that many of mine are now “Unavailable”, “Expired” or I’m “Not Authorised” to view them. This is only on my older responses which date back to late October/early November of this year. Are they only kept for a certain time?

Also, is there a way to get back the ones which are currently not showing? This will be a significant problem if they are gone for good especially as we had been downloading them using the export facility, but not checked (as we usually work with survey responses using the web interface), and these attachments do not seem to be included.

If there is a limitation on how long data is stored then it should be clearly published, and if this is the case then we will need to setup our own server to ensure reliable data storage.

Please advise