Failing to ignore Content Handling start pattern

[DavidAccola]

DIffMerge is failing to ignore the Start Pattern for Content Handling it should be ignoring. This is making it impossible to correctly ignore code comments.

Rep steps:

• -Install Diffmerge v5.0.0.1 (DiffMerge_5.0.0.1.dev_x64.msi)
• -Create an old.txt

abc
def

-Create a new.txt

abc
<!--comment test-->
def

-Open File Diff > Select files > OK
-File > Change Ruleset > XML FIles
Note that DiffMerge believes there is 1 change: the beginning of the comment <!--
It correctly ignores the rest of the comment, but not its Start Pattern.

Expectation:
DiffMerge ought to be ignoring the full comment, including <!--, as a part of the default Content Handling in the default XML Files ruleset.

(My use case is actually SQL comments, but it's easier to demonstrate with the default XML File ruleset.)

Is this a bug, or is there some setting I should be changing from the defaults to make this work? I have set all settings to default. This is my first time trying out DiffMerge, so I could be missing something.