The 'media on server' will only show files that are in the import or uploads directory, not existing processed media as in ca_object_representations. To get files into the import directory, you can copy them directly on the server, or in this case it seems this is the directory the application uploads it to before it processes it. The uploads directory is for the media uploader tool (under import menu if enabled). When it processes the media it puts files into the tmp directory before storing the processed files in media/collectiveaccess.
At least using the new UI, it is uploading it, but nothing happening from there. The classic only uploads the file when you hit save and not sure if this is actually uploading anything.
As javascript is client side, you need to look in the browser developer tools, usually under the console in these. right click in the window and select 'Inspect' or 'developer tools' or something like that.
The errors above, are they triggered on a record with no media attached, or a record that you are attempted to add media to, but is failing?
Since you are using Windows are your server, I would suggest doing a diff on the external_applications.conf between the default and local, as there would be new entries in that you'll need to update to the executable in windows. In particular, the format of the file has changed to using lists instead of single value.
in app.conf, check the setting of batch_media_import_root_directory = <ca_base_dir>/import If php needs the paths used to be the correct direction of slashes, check what you have set for the base_dir in either global.conf or setup.php
There is very old documentation that talks about needing to change all references to /dev/null in the code to /$null. No idea if this is still relevant or not.
Not sure how much more helpful I can be from this point, as I said earlier, CollectiveAccess is not developed, tested or supported on Windows.
