By design, the WooCommerce price filter widget displays a little bar with a handle you can drag to set a price range to filter the products by. In some situations, you may see two input fields to enter the price range instead.
If your host has an outdaed MOD_SECURITY core ruleset, this issue and others will occur. More information here.
The BEST option is to get your host to update the rule set. Contact your hosting provider for assistance with this.
If your host is not responsive or refuses to fix the issue, you can attempt too do it yourself with the following plugin, which is authored and maintained by the WooCommerce crew. Download the zip and install it under> .
For support or questions about the plugin, please contact WooCommerce support.