@Phineas ,
To answer the question you posted regarding displaying the file name and thumbnail, you appear to be filtering a collection Activity_Documents_Collection, rather than the 'Shared Documents' Library, so have you looked in the collection to see if the file is present. I can assure you that if it is then
ThisItem.'{Thumbnail}'.Large
will display the image and
ThisItem.'File name with extension'
will display the file name.
Please click Accept as solution if my post helped you solve your issue. This will help others find it more readily. It also closes the item. If the content was useful in other ways, please consider giving it Thumbs Up.
MVP (Business Applications) Visit my blog Practical Power Apps