Object reference not set to an instance of an object. during perfect match

Hello,

While we were trying to apply Perfect Match in a project, we received the all time classic "Object reference not set to an instance of an object." error message.

More details can be found in the file below.

/cfs-file/__key/communityserver-discussions-components-files/90/sdlerror_2D00_2019814_2D00_14h21m21s.sdlerror.xml.zip

Source is an HTML file (processed with HTML 5 filter), and the only difference between old and new source is some "span" tags, see images below.

Old:

New:

Any idea why this is happening?