Updated to mySQL v5.7.24 and this seems to have broken GC. I now get this error when saving an N2N record:
al error: Uncaught PDOException: SQLSTATE: Invalid datetime format: 1292 Truncated incorrect DOUBLE value: '63,1' in F:\Programming\Web\GroceryCrud\libraries\zendframework\zend-db\src\Adapter\Driver\Pdo\Statement.php on line 244
Looked at the SQL logs and this is the failing statement, specifically NOT IN ('63,1'):
DELETE FROM `game_uses_item` WHERE `ItemID` = '440' AND `GameID` NOT IN ('63,1')
This worked fine in mySQL v5.7.14.