According to date_time.txt:

For the startOfWeek() function the result depends upon your locale. For example, in Europe the first day
of the week is generally considered to be Monday, while in the USA it is considered to be Sunday.

But, seem not the case where only able to search start on Sunday issue.

Steps to reproduce the problem:

1. Change locale to UK.
2. Configure JIRA environment using this argument:

   -Duser.language=en -Duser.country=DK -Duser.timezone=Europe/Copenhagen

3. Search using this JQL:

   createdDate > startOfWeek() AND createdDate < endOfWeek()
   

4. Still can show last week Sunday issue.