In some cases you might encounter a different interpretation of date values when loading data from Salesforce with the native Qlik Salesforce Connector. The result might be that certain dates have decimals and appear to be timestamps in Qlik Sense, although the original date from Salesforce is just a pure date. Due to the decimals the data gets rounded to the previous day when loading data from Salesforce.
The issue is related to a known BUG - QVXSF-551 in Version 14.1 which is fixed in the February 2018 Release of Qlik Sense.
A potential workaround is to use the Qlik Function "Ceil" directly in the Script to round up the date value when loading the data over Salesforce Connector 14.1 or upgrade to Qlik Sense February 2018.