Try using a different browser (not IE) and for IE, press your ALT key and select the Tools menu and then the Compatibility View Settings item. On the screen which comes up, uncheck the "Display intranet sites in Compatibility View" option and click the Close button. Finally, reload the page (Ctrl-F5) and try your upload again.

HTH,
Joe D.

you need to use web browser dev tools to find and solve the script errors

use the console for checking script errors and the network tab to check for script files that fail to load

for example since it is an intranet you may need to host the jquery files locally if it cannot be loaded from the internet

You could still be having javascript issues or maybe css issues. I can assist you with this if you contact me at joe (at) i7media {dot} com.

Thanks,
Joe D.