Hello,
We can successfully use the Invoke Web Service action when an API requires only one item in the Custom headers field (like "Authorization"), but when two items are required, the connection attempt fails due to an "invalid credentials" error. Using the same header items, the connection is successful in the Postman app so we feel they are correct.
We feel that Power Automate Desktop may be incorrectly formatting the header values when it sends the request or we are incorrectly formatting them in the Custom headers field. To add to this concern, one of the headers requires a space in its value ("Authorization: Bearer [KEY]"):

The credentials have to be base 64 encoded, so using the HTTP Authentication section does not appear to be an option:

We have no way to viewing the request that is actually being sent out by Power Automate Desktop (I don't believe this is possible to see from within the app), but again the request works fine from Postman. We have attempted using commas, semicolons, newlines, etc. to delimit the two header lines. We have also attempted to include the header string in a variable and then reference the variable from the Custom headers field. Unfortunately, nothing has worked so far.
Is anyone aware of how to view a request, how to format the text in the Custom headers field when there are more than one header and a space in value, or any other idea for how to resolve this issue? Thanks!