Qlik Sense can process a maximum of 1,048,576 (2^20) characters by row when loading data from a CSV file. If a row in the source CSV file is longer than this limit, Qlik Sense automatically breaks it to multiple rows in the loaded table.
This doesn't happen when loading another file format (like XML) or loading the same CSV file in QlikView.
Resolution
To increase the maximum length, please set parameter LongestPossibleLine in Settings.ini file of Qlik Sense Engine to a higher value than 1048576.
See How to modify Qlik Sense Engine's Settings.ini for detailed instructions of changing parameters in Settings.ini.
Cause
Qlik Sense engine supports up to 512 Megabytes (512*1024*1024) as line length. Script reload can handle strings up to this length in a single data cell. However, when using the data selection wizard, such long string may break the web socket. Therefore, maximum string length is limited to 1,048,576 characters to avoid this web socket issue.
Environment
Qlik Sense Enterprise on Windows