Can't move a Feature Service using ago

[RayVidalis]

Hello,

I'm trying to use ago to transfer a "Feature Service (Hosted)"  from Online to Portal.
So I tried both from the publicly hosted version ->
ArcGIS Online Assistant 
as well as my self hosted one (wanted to make sure that it's not a networking issue)

My first problem is that my ArcGIS Server timeouts if the Feature Service is big e.g. >30Mb.
I guess this might be related to my tomcat running the webadaptors and I will have to increase the POST request max size to fix it.

But where I'm really stuck is that for a smaller Feature service ago seems to work and reports success.
After that I can see my Feature Service both in my ArcGIS Portal as well as in my ArcGIS Server.
The problem is that when I go to the "Data" tab in portal I can see just the column names but no data in the rows.

Also my ArcGIS Server log shows:

SEVERE -- Error processing request Service Hosted/DEMO/FeatureServer not started  -- Rest

Any clues?

Thank you

[RayVidalis]

so my requirement is to deep copy and not create just references. 

After trying many ways I had partial success with the clone_items function ->

arcgis.gis module — arcgis 1.7.0 documentation 

data gets copied but now I encounter the following:

ERROR: Inconsistency in the Field Definitions found.

which causes the entire copy operation to roll back