Hi!
This usually happens if a 3rd party plugin invokes a javascript error before rendering. It can also happen if the theme javascript files are loaded on the back-end as well (where they shouldn’t).
I can’t tell exactly unless I see it, but you can try 2 things:
- Swtich the theme temporary to the default, and see if it works then.
- Turn off every other plugin but the search and try then (or you can turn them off 1 by 1)
If it doesn’t help, you can include temporary back-end details to your ticket and I may be able to tell where the error originates from by checking the error console.