Hi Dario,
We are able to reproduce the issue “Exception thrown while creating StackingColumnSeries dynamically from code behind”, we have created incident "127350" for this reported issue. Our support engineer will assist you through incident under your Direct Trac account.
Our Direct Trac support system can be accessed from the following link:
https://www.syncfusion.com/account/login?ReturnUrl=%2fsupport%2fdirecttrac%2fincidents
You can define primary axis and secondary axis for avoid this null reference exception in StackingColumnSeries.
Please let us know if you require further assistance on this.
Regards,
Sumathi.J