The previous discussion (see link) has been closed but I have had problems with this issue when updating an alias file:
https://moodle.org/mod/forum/discuss.php?d=271328
However I think that the trick is to update the file as described elsewhere (i.e. overwrite with same name file) and then wait a little while perhaps 15-30 mins for the alias copies to update themselves. Can anyone confirm if this is the case? It seems that the update to an alias copy is controlled by a cron process somewhere?
The problem is you update the source file and the alias copies don't seem to change, but I found if I waited they did...? I'd be interested in hearing other experiences.
Happy Moodling,
Jim