Mmmm🤔, not sure why this did not work. Let me try on my end. 
Forwarding now Excellion
Could be client you’re using, or pub key error.
If on snort.social, you can search by username when typing @ and you'll get autocompletion to choose user you want to tag 

 Worked :) your message has been successfully forwarded to Excellion. Thank you for using nostr today. Ok, that’s my last customer service job for the night, off to bed ✨ 

 Good night and thanks for your service! 

 Could be, I was using Android App Nostros  

 Yeah, it sounds like Android App Nostros might use a different tagging feature. Let me see if I can find out on the grapevine🍇 what that feature is and I’ll get back to ya :) 

 👍 

 here's the code that appears to be handling the replacement in nostros. https://github.com/KoalaSat/nostros/blob/main/frontend/Components/TextContent/index.tsx#L60. i think the issue might be that it doesn't follow nip-08. the pubkey should start with an octothorpe.
 

 Thank you 🙏 looks like w3irdrobot has found the answer for you williamsantiago:)