Hello,
This could happen due to any number of problems. It looks like JavaScript has crashed with an error.
1. Please check your browser’s console for errors and let me know what you found. If some other component is producing a JavaScript error, you must fix or eliminate that component.
2. Visit the JSON API endpoint get_coins_info. Use your browser to go to https://example.com/?__wallets_apiversion=3&__wallets_action=get_coins_info (substitute example.com with your own domain). What do you get back? If you don’t get back a proper JSON response, this could mean that there is an issue with caching plugins, the web server configuration, or even something else.
Show me what you found in 1 and 2 and I will advise.
with regards