if you need to convey an urgent message to someone, make a priv code and put your message in there and ping that person.
Else, i recommend you to use an actual messaging app, as sololearn always has an issue specially with messaging. Better use some other platform.
Please dont panic too much, such bugs shouldn't deter you from making some codes. Focus on programming. Use discord/ instagram/ etc for messaging.
If the problem persists, mail to sololearn at [email protected]