You are referring to the price dropdown on the page you linked to, correct?
I can see that it is not working, though it is not clear why from the front end alone.
The first step would be to rule out any conflicts with any 3rd-party code that could be breaking the filtering feature (a plugin update could explain why this stopped working, for example).
Ideally on a staging or development server, could you disable all non-Toolset plugins and test the page again? If it still doesn't work, try switching theme to twentytwentyone.
If the search filter does start working then it should be possible to identify where the conflict comes from by re-activating your plugins one at a time, or in batches, and re-testing.
Let us know what you find so we can see how to proceed.
Can you please share admin access details and tell me what view you are using.
*** Please make a FULL BACKUP of your database and website.***
I would also eventually need to request temporary access (WP-Admin and FTP) to your site. Preferably to a test site where the problem has been replicated if possible in order to be of better help and check if some configurations might need to be changed.
I have set the next reply to private which means only you and I have access to it.