The check icons are loading fine on my end:
Did you mean you couldn't change them to other icons?
Please follow up the steps below:
- Ensure everything is up to date according to our version compatibility list here. Please follow the best practices when updating your theme and plugins. Click here for more information.
- Go to X > Settings and click on the Clear Style Cache button.
- If you're using a CDN(ex: CloudFlare), please clear the CDN's cache and disable optimization services. For the CloudFlare you also need to follow the steps below besides the developer mode: https://xthemetips.com/using-cloudflare-rocket-loader-with-x-pro-and-x5/928/1
- Test for a plugin conflict. You can do this by deactivating all third-party plugins, and see if the problem remains. If it's fixed, you'll know a plugin caused the problem, and you can narrow down which one by reactivating them one at a time.
- Switch to the parent theme to check if the issue persists.
- Turn off all the cache plugins.
If you still have problems kindly get back to us with the result of the steps above and URL/User/Pass of your WordPress dashboard using the Secure Note functionality of the post to follow up the case.