SYMPTOM:
In Strategy Analytics Enterprise 9.4.x, users may select a different language locale for the Number and Date Format in the Preferences page, like shown below:

In this example, with French (Switzerland) selected, the expected format for dates is:
dd.mm.yyyy
mm/dd/yyyy

This issue may also cause correctly formatted dates being rejected in a date prompt, after the date format has been customized (see KB440717).
CAUSE:
This is a known issue with Strategy Analytics Enterprise Web 9.4.x.
ACTION:
This issue has been addressed in build 9.5.1000.0052. Consider upgrading to 9.5.1 or newer to take full advantage of this fix.
WORKAROUND:
Instead of an Attribute Element prompt, users can create a Qualification prompt to achieve the same filtering and still maintain the language locale, like shown below:

KB45625