Notification emails (for comments) don't include diff

Related to CONF-8945 most users expect that they will get the diff in an email.

Unforunatly, there seems to be some circumstances, these diffs are not sent.

Example: someone writes a comment on a page I'm watching. This notification includes the comment. But when he edits his comment, the mail informs me that XY has edited his comment, but there is no diff included.

I'm not sure / I don't have a mail left in my inbox at the moment, but I could bet that I've seen another case where page-edits are not sent out with diff but only "page was edited".
Mostly I'm getting these notification from atlassian documentation system itself, if someone is editing my watched pages like EOS https://confluence.atlassian.com/x/HQCID
This issue not happened when 4.3.2 was installed on https://confluence.atlassian.com/