please watch videos for understanding
(https://youtu.be/tuqM0_0hXdw?t=338)
Hello,
This is a duplicate of Basic report - print repeated value on group change doesn’t appear to be working. Posting additional questions on an already reported bug (tdf#103387 was original report) will not get this resolved any faster. This site is simply other users trying to help and not necessarily developers.
Sorry 