Hopefully, this guide will help you finally access your inbox the normal way & finally respond to/accept incoming messages, as well as send them.
While it is unclear why and where the original problem is coming from, you can overcome it.
- Switch To Another Browser. Experience shows that when we are dealing with the Internet, any sort of issues can happen and we might need to use another browser as a simple back-up. It is always a great idea not to rely on one internet browser alone, but to have a couple on your laptop, one main and a couple as a useful extra. You never know when you might need to use them. If you are using Mozilla Firefox, you can have so many extra features, that they might start conflicting with gaming, or the game just does not deal with Firefox well, who knows. In any case, open the game in another browser and see what happens to your problem. For the issue with responding to requests, try simple browsers, such as Google Chrome, Yandex.
- File a Bug Report. If a change of browser is having no effect whatsoever, then the road is clear: you cannot evade the issue and need outside help. This when you should file a bug report to the game creators. Hopefully, the issue will be resolved after some time.