Channel problems

[noobalert]

I have 2 problems: 

1. Whenever I send a message through a private channel, it will show on my end as 'Message not sent' but on my colleague's side it shows 

2. I do not receive any chat from the channel but private chats are fine 

What I've done: 

1. Left the channel and was readded 

2. Deleting Zoom and reinstalling 

Any suggestions do help, please