Line missing from PDF export using JIRA Issues Macro

There's a blank space where the line should be appearing in JIRA Issues Macro when exporting a page to PDF. This is happening on the top line only. The rest of the lines are displaying properly.

Looking at the page everything appears to be working properly:

However, when we export the page to PDF, it seems that the top line under JIRA's custom fields are not showing up:

It only seems to appear under JIRA's system fields. This started to happening only a few weeks ago. This can be reproduced by exporting the page to PDF by going through the page itself or by exporting it from the space admin area (Content Tools > Export > PDF > Custom Export > Page).