I created a lesson activity in Moodle 3.3.4 with only one Matching Question. I hand typed the text into the fields to make sure the issue was not coming from Word related text being copied and pasted. However, when the question is attempted it never shows either correct or incorrect response.
When I enable Debug mode and attempt the question I get the message below,
"Warning: Invalid argument supplied for foreach() in /var/www/html/moodle/mod/lesson/locallib.php on line 4105"