Steps to reproduce:

1) Create a page with some headings and the TOC macro on top:

2) Page view with TOC macro:

3) Create JIRA issue by highlighting a heading:

4) Problem occurs:

5) Remove TOC from page:

6) Page view without TOC macro:

7) Create JIRA issue by highlighting another heading (not the one from step 3):

8) Creating and adding issue is successful. JIRA Issue macro is added to heading:

9) JIRA Issue macro is inserted besides the heading:

10) Insert TOC again. TOC is displayed without a problem: