possibly down to the model not understanding it can read .tsx files, you can try renaming them to .txt or you can try pasting the file contents into the chat directly.
you can also tell the model that it CAN read the files, file uplaoding is still in beta test, so there will be times when the model is confused by file types and even by the fact that files can be uploaded at all as that is a new feature. These issues will get better with time and training so please be bare with it.