Completely new to Power Automate:
My flow responds to the arrival of an email with a pdf attachment, and whose body contains certain key values, by POSTing that attachment to an api in a remote system. More precisely, it makes an api call to check if the remote system already has a row matching these keys, and if it does not, then it makes two more calls:
A. One api call to create a new row to contain these keys (this works fine)
B. Another api call, to a different endpoint, to attach the pdf to this new row <-- resulting pdf is corrupt
So (B) is a POST whose body is the content of the PDF.
All this runs fine end to end, but the pdf is unreadable (that is, as a pdf). If I compare it to the original (that is, in a text editor) they don't match. The file produced by (b) is also much larger, almost twice the size of the original.
I've already validated (not shown here) that there only one attachment, ending in pdf. Include Attachments is Yes.
Here I've created the new row (A) and I'm putting together the post to B.



When I download the attachment content the input does not match the output, in that the output has a leading 'body' key.

Input
{"name":"attachmentContent","value":"%PDF-1.7\n%����\n4 0 obj\n<</Subtype/Image/Width 1728/Output
{"body":{"name":"attachmentContent","value":"%PDF-1.7\n%����\n4 0 obj\n<</Subtype/Image/Width 1728/I also tried multipart, following several examples posted here, but the result was no different.
What's going on here? I appreciate your help!