I keep getting below error while using Vadims solution, and i am able to get the URL's properly. I must be missing something:
Error Getting List Item Attachment. Object reference not set to an instance of an object.
Finally got it after MULTIPLE tests...
The problem was with the internal list name MUST MATCH the list title. In my case the internal list name was ValidationTest and my list title was Validation Test. Finally after several failures i changed the list title to match the internal list name as ValidationTest and it worked!! Thank you for even trying to help me out, your guys are awesome!
Yes, @allan is right. If you use the Vadim action to get file Base64, your list Title must match the list URL.
In the code of this action (I have decompile the dll of the wsp), the URL of the list is re-build with the title, so if you have space or rename your list after his creation, this will not work.