Hi Manolo,
Thanks for contacting us.
We have validated the reported issue in the EJ2 uploader control, and we have considered this as a defect in our end. The fix for the issue will be included in our upcoming patch release which is expected to be rolled out in the month of April 2019. You can now track the current status of the report, review the proposed resolution timeline, and contact us for any further inquiries through this link:
https://www.syncfusion.com/feedback/5467/
Regards,
Prince