had problems with this myself as well yesterday; found following 'solution'.... wait for a little while, REBOOT the maxisys and retry. You have to reboot, if not, no change at all, but after reboot the files went without a sweat.
Autel also send me a mail stating that due to a lot of uploads the server is harder tot reach. That is something I find hard to believe... it may be true but it is so simple to fix that the customer would only have a few days of trouble before you expand your server capacity and al issues would be gone. Anyway, it is descent from Autel to let me know, like more reactions they send out lately, things are improving as it seems.