Uploading Arduino UNO from Makeblock editor online



I am facing an issue when trying either to update the FW or upload a simple program to my Arduino Uno board from mblock online editor.
It seems that the board is connected but as soon as I try to upload it disconnets and get the following message:

Any clue?

Thanks in advance for the support


Please try mBlock 5 online version: https://ide.makeblock.com/#/



Thanks, I tried but no way. I am getting this now:


Sorry for the late. Could you please take a video for me? We test with Arduino Uno, it works.