Inside a Jira ticket, whenever I post a link to a file, a commit or anything on Bitbucket, it says "Can't find link".

I see all Repositories, PRs etc. under the "Code" Menu point though.
In the Atlassian Admin, under "DVCS accounts", I see the linked repository, too.
So Jira and Bitbucket seem to be connected, but I cannot find the setting to enable links inside the Jira Tickets. Does anyone know what the issue may be?