I did a clean install of MediaWiki 1.33 on Windows Server 2016. Installed the extension via composer.local.json, ran composer update --no-dev and added the wfLoadExtension( 'SimpleBatchUpload' );
line to LocalSettings.php.
Extension is shown on the Version page, but Special:BatchUpload only shows the text "Select files (or drop them here)...", a button with text "Choose Files" and "No file chosen".
The error log shows the following:
[resourceloader] Unexpected general module "ext.SimpleBatchUpload" in styles queue. [resourceloader] Unexpected general module "ext.SimpleBatchUpload.jquery-file-upload" in styles queue.
I didn't have this problem in MW 1.31. Has there been any breaking changes since?