Steps to reproduce

Create a new survey.
Add a Multiple short text question (type Q).
Add one or more subquestions.
Activate the survey and submit at least one response.
Open Statistics.
Enable "Show text responses inline".(See the attached settings screenshot)
Generate the statistics (pdf or excel).

Expected result

Statistics should be generated successfully and the text responses of the Multiple short text question should be displayed inline.

Actual result

The Statistics request fails with HTTP 500.

The server log contains an SQL error similar to:

Unknown column 'QQ2412_S2419' in 'WHERE'

The actual response-table column is:

Q2412_S2419

Additional findings

The issue can be reproduced specifically with Multiple short text (Q) questions.

The relevant code path in application/helpers/admin/statistics_helper.php handles Multiple short text together with the other text question types:

elseif ($outputs['qtype'] == Question::QT_S_SHORT_FREE_TEXT
|| $outputs['qtype'] == Question::QT_U_HUGE_FREE_TEXT
|| $outputs['qtype'] == Question::QT_T_LONG_FREE_TEXT
|| $outputs['qtype'] == Question::QT_Q_MULTIPLE_SHORT_TEXT)

When showtextinline is enabled, it calls:

$result2 = $this->_listcolumn($surveyid, $sColumnName);

The malformed column name appears to be introduced somewhere in this Statistics / _listcolumn() code path.