Joplin for Android, v 1.5.1
for any file attachments a long press on the file (icon) should open Android's share menu, rather than try to open the file based on file type associations. This provides more options, enables saving the file directly, in particular in cases where an appropriate app is not installed.
[see post "attachments - in and out", table at the end of the post, fields D16, D17 and D18, and related text]