The attachment file content is not synchronized after modification, please assist

I have recently tried to highlight a number of problems with attachments across all platforms - in a post called attachments - in and out.

Some of the problems listed there seem related. Could we merge these threads, so that the devs can find it all on one place should they ever decide to clean it up ?

(@roman_r_m : unfortunately the recent quick fix of one problem in Android related to attachments didn't work -> see github)