when somebody sends me a message on xbox i can see it but when i click on it , it doesn't...

My name is Fernando I'm an independent consultant, I'm happy to help

The link below has some information and solutions that can help you in this case.

https://support.xbox.com/help/friends-social-activity/share-socialize/send-receive-messages-xbox-one

Hope I helped and see you soon

Sometimes the notifications don't go out correctly. If you are in the "insider" program it may be a temporary failure. If you are not in that program it can be a temporary problem.

If it only happens with the same person, try to remove yourself from friends and do it again.

No I never answered my own question. If you read carefully, I said I know what to do to unblock somebody. Then I asked how can I unblock somebody when we've blocked each other? This means I explained that I know how to unblock somebody when he hasn't
blocked me. This means things are harder to deal with when we've blocked each other because if I send him a message, invite or friends request, he won't get either of them so that I can unblock him, same thing visa-versa if he tries to unblock me. I was
asking if there's another way to unblock somebody when he's also blocked me, such as, is there a block list for me to unblock him from or can I unblock him by contacting Xbox Live?

There were two apps in the google app store, an xbox app and an xbox beta app. the beta one crashes when selecting messages or it just says something went wrong and doesn't display any messages. I tried using the other xbox app and
that seems to be sending messages ok (using a pretty old Samsung Galaxy 2 tablet so I can understand having issues there). On the desktop pc I can send messages on xbox.com but I can't tell if they have gone through because my message history on xbox.com isn't
updating so I can't see what I sent, I have to go onto the app to see if the message was sent. the windows 10 app works fine for everything apart from the messages, when I click on the message icon the app crashes.

When I am signed in, I can see messages that people send me. But I cannot respond to them, even people on my friend list. When I try it tells me to go to the xbox support website where it asks for a phone number to send a text message to.