While visiting a page like:
/moodle/mod/quiz/report.php?id=3325&mode=statistics&qid=42975

I get the following instead of the Analysis of Responses table:

Debug info: Object of class core_question\statistics\responses\analysis_for_actual_response could not be converted to string
Error code: codingerror
Stack trace:
line 393 of /lib/setuplib.php: coding_exception thrown
line 110 of /question/classes/statistics/responses/analysis_for_class.php: call to default_error_handler()
line 98 of /question/classes/statistics/responses/analysis_for_subpart.php: call to core_question\statistics\responses\analysis_for_class->has_actual_responses()
line 133 of /question/classes/statistics/responses/analysis_for_question.php: call to core_question\statistics\responses\analysis_for_subpart->has_actual_responses()
line 83 of /mod/quiz/report/statistics/statistics_question_table.php: call to core_question\statistics\responses\analysis_for_question->has_actual_responses()
line 373 of /mod/quiz/report/statistics/report.php: call to quiz_statistics_question_table->question_setup()
line 220 of /mod/quiz/report/statistics/report.php: call to quiz_statistics_report->output_individual_question_response_analysis()
line 100 of /mod/quiz/report.php: call to quiz_statistics_report->display()

It does not do this with every question in the quiz but with a number of them. I've found the issue in a second quiz but only with short answer questions so far.

I'm happy to poke around more but I've been randomly poking through my course for a while look at statistic reports and don't have any thoughts on what might be different about those questions/quizzes.