All machines are under my company's ownership

Using an autoscaler service(on 24/7 EC2 machine)
that triggers EC2 workers (with an AMI I saved prior to activation)

Hope that helps

EmbarrassedSpider34 "self-hosted" in this context can also include AWS EC2 - the question is are you using some sort of hosted service or an open-source ClearML Server you (or your company) have self-installed

As a matter of fact, all my tasks are "running" state although some of them have failed

no, it is AWS EC2

Is it a self hosted server?

folder is rather small.
3.5MB
Am able to see it in the artifacts.
but can't download it (the address is wrong)

Also try looking into the resource management on the machine. Do you see traffic going through the network?

It can take some time if the file is very large or if the folder is very large. This can also depend on the connectivity. If the folder is very large please consider the fact that zipping it also can be resource demanding.

How long has it been hanging and how large is it the folder?