Links to other issues are broken in a few ways:
Links added by 'issue' link are wrong. For example, when adding the link to issue 401 from issue 402, the link is stored as .../402/401 and links to current issue instead. Minor issue is that default link name is URL, so it looks like https://bitbucket.org... issue. Maybe the arguments got swapped?
Duplicate does not have link, instead, ugly <<issue 452>> is shown.
<number> is still converted to issue, but without a link and with ugly <<issue 452> formatting.
I feel like all these errors have common cause.