Hi again SuccessfulKoala55 Sorry for a late response. Thanks for your help so far! I understand that it's a weird problem and probably it won't be resolved in this discussion but just in case I've checked the mongodb entry for the task after cloning, after clearing of the fields and after sending it for execution.
After clone:
{ "_id" : "b94657b00adf41dd971426f51d7b9373", "container" : { "image" : "{image_name}", "arguments" : "--ipc=host -v /home/{username}/clearml.conf:/workdir/clearml.conf -e CLEARML_AGENT_SKIP_PYTHON_ENV_INSTALL=1", "setup_shell_script" : "" } }
After clear:
{ "_id" : "b94657b00adf41dd971426f51d7b9373", "container" : { "image" : "", "arguments" : "", "setup_shell_script" : "" } }
After enqueue:
{ "_id" : "b94657b00adf41dd971426f51d7b9373", "container" : { "image" : "{image_name}", "arguments" : "", "setup_shell_script" : "" } }(actual image name and username are replaced with {image_name} and {username} in the message)

I've sent it just in case. Anyway, appreciate you spent a lot of your time on me already, so it's ok to drop it I guess.