I'm hoping to build a flow that will give users viewing access to a few Lists that are required for a Power App. In doing so, I tried to use the Send an HTTP request action to 1) get the user's principal id and then 2) add role assignment (View) to a SharePoint List. Everything looks to work, I can GET the id and run the "add role assignment" POST request, but then when I check the List's sharing settings, the Flow has added a different user entirely (albeit with the correct role). When I check the output of the HTTP request that GETs the id, it shows the correct user's information. I added a test step to search users by id, and it also returns the correct user. But once it gets put into the HTTP POST to change List settings, for some reason it grabs the wrong user and slaps it onto the List.
(Alternatively, if anyone knows of a way to have people who use a Power App still see combobox / dropdown selections from a List, without having Viewing rights to the List, that would solve all my problems.)
Flow steps in question.
Output of the "Get Principal Id" step.
HTTP request to add sharing rights to the User Principal Id.
SharePoint List access list.
