There is a known issue with file upload fields in Instagram’s iOS app (as of June 2018) when a link is clicked from a direct message. When a user opens a link from a direct message, the file upload field displays, but when they select a photo to upload, it shows briefly and then is removed making it impossible to submit a photo. This appears to be a bug in Instagram’s in-app browser implementation. The problem does not occur when links are clicked from the profile bio section.
File upload not possible from link sent via direct message in Instagram iOS app
Updated on October 31, 2018