Check the console log to find a huge amount of errors saying the following:
XMLHttpRequest cannot load https://api.jublo.net/codebird/oauth2/token. Response to preflight request doesn't pass access control check: No 'Access-Control-Allow-Origin' header is present on the requested resource. Origin 'https://pavelk2.github.io' is therefore not allowed access. The response had HTTP status code 502.
This is affecting my own sites, however it can also be seen on the demo site https://pavelk2.github.io/social-feed-example/.
Check the console log to find a huge amount of errors saying the following: XMLHttpRequest cannot load https://api.jublo.net/codebird/oauth2/token. Response to preflight request doesn't pass access control check: No 'Access-Control-Allow-Origin' header is present on the requested resource. Origin 'https://pavelk2.github.io' is therefore not allowed access. The response had HTTP status code 502.