Hi Luca,
I tried to implement the mentioned objective in a sample application but couldn't able to achieve it after various trials..
As a work around, I guess if you just append two records (missing series records) explicitly for Saturday and Sunday (i.e. 10 - 11 Oct in your case) record with 0 DataPoint value, the output will be a correct graph.
See this sample app - LineChart
Refer this post (It didn't worked for me!): https://www.outsystems.com/forums/discussion/62372/chart-how-to-hide-data-label-having-value-zero/#Post243586
Hope this helps you!
Kind regards,
Benjith Sam