O365 Workflow not able to read/write via REST to list on a subsite

Question

Hi Guys,
I'm facing an issue that i would like to read and the write to a list which is located on a sub site (same site collection https://server/sites/web/subsite/) with a Workflow using REST API (located in https://server/sites/web/). Let me give you a background.
I'm using o365 as environment so i'm developing the workflow in SharePoint designer.
What the list WF is doing:
it's making a simple GET REST query https://server/sites/web/subsite/_api/web/lists/getbytitle('X_List')/items(1) in App Step to read list items on the sub site. It returns in the Response Code: NotFound (on Sharepoint on premise it's working). So the
array is empty. When i'm doing the same for the for the same site where the WF is located then the Response Code is OK.
Funny thing is that when i'm doing a call like this https://server/sites/web/subsite/_api/web/lists/getbytitle('X_List')/itemcount then the Response Code is OK. It returns the correct amount of items in the list.
I've granted also Full Control to the workflow according to the
msdn but it did not resolve it.
Is there a way to check the permissions for the workflow? it looks like it has not the proper permission for the subsite to see the list items.
Thanks,
Wojtek
Wojti

Answer 1

Hi Dennis,
thanks for you input. please see my comments inline.
Best regards,
Wojtek
Hi,
For a better troubleshooting, I suggest you to do as follows:
1. Try to access the URL below in IE directly.
https://server/sites/web/subsite/_api/web/lists/getbytitle('X_List')/items(1)
done. i'm able to enter it (done via POSTMAN)
2. Check whether the list item(ID=1) exists.
the item is there 
3. Create a new custom list and add a new item to the list, then access it again.
done. Tests results are postive
Best regards
Dennis Guo
TechNet Community Support
Wojti