Hey there,
I know this is an old thread(let me know if I need to repost somewhere else), but this problem is still happening...
I did however stumble upon an easy work-around/magic-trick that will essentially re-link any unlinked text AND object elements in the symbol:
1. Select the unlinked(dashed line) text/element, position it where it needs to be...
2. Then cmd + J (ctrl + J) and viola! The duplicated object is now back in sync with everything else.
3. Delete the original "problem" element and your back in business.
Hopefully this works for the rest of you, I've been losing hair over this myself! lol