Hi there, dalemcnelly!
Thanks for reaching out to the Apple Support Communities! It sounds like you're having an issue using inline replies and mentions. Check out this article to Use inline replies and mentions in Messages on your iPhone, iPad, and iPod touch. For mentions:
- Open a Messages conversation.
- Type a contact's name, then tap the name when it appears. Or type @ followed by their name.
Depending on your contact's settings, a mention can notify them even if they've muted the conversation. To change this notification setting, go to Settings > Messages, then turn Notify Me on or off."
Per the article, there will not be a pop-up unless you tap on the name you have typed.
For the issue with the option to reply not coming up in a group message for a specific contact, is this contact using an Apple device or non-Apple device? if they are Apple users, be sure they have installed iOS 14 on their device and if you still don't have the option to reply inline to them, we recommend checking out this article with steps for How to force an app to close on your iPhone, iPad, or iPod touch and quit the Messages app. Once it’s closed, Restart your iPhone and test to see if the issues are still going on with that contact.
Let us know the results and have a great day!