@Digital
Could you share more details and screenshots about the flow and app?
I have made a test. bulk upload image to SP documents, and return the File ID. Hope this help.
1. check the flow steps

2. add an Add Picture control, set OnSelect property of AddMediaButton1 as below, all JSONs with ImageName and Image are saved into the collection.
Collect(MyCollection,{JS:JSON({FileName:AddMediaButton1.FileName,File:UploadedImage1.Image},JSONFormat.IncludeBinaryData)})
3. add a button, set OnSelect as below, save the return ID into the collection.
ClearCollect(ReturnID,ForAll(MyCollection,SPdoc.Run(JS).fileid))


Sik