When using newlines in report descriptions for PMs, the newlines are not displayed in the report that is displayed to the moderator. For example
This is the first line of text.
This is the second line of text.
will be displayed as
This is the firstline of text. This is the second line of text.
When posts are reported, this will instead appear as expected.
In addition, when including links within the report text, these are not automatically made clickable for the moderator when a PM is reported, but they are made clickable when a post is reported.
The fix to both of these consists of merely one additional line of code in includes/mcp/mcp_pm_reports.php:
$report['report_text'] = make_clickable(bbcode_nl2br($report['report_text']));
$message = bbcode_nl2br($message);
$message = smiley_text($message);