Hi @agusdp,
I hope you are well today and thanks for posting here.
It’s working fine on my test site using the latest version of Sparkling theme.
Please make sure that you are using the latest version of Sparkling theme and set the sidebar position on the following path.
Admin Area -> Apperance -> Customize -> Sparkling Options -> Layout options
If it doesn’t work for you setting sidebar as described above then this can be due to plugin conflict on your site so please try temporary deactivating all plugins and see whether everything works fine and then enable the plugins one by one to see which plugin is conflicting if any.
Best Regards,
Movin