We tried it from our end and it worked for us.
{ type: "AdaptiveCard", $schema: "http://adaptivecards.io/schemas/adaptive-card.json", version: "1.0", body: [ { type: "TextBlock", size: "Medium", weight: "Bolder", text: "Hi <at>MOD Administrator</at> This is new feature in Adaptive Card version 1.2 Please test..." } ], msteams: { entities: [ { type: "mention", text: "<at>MOD Administrator</at>", mentioned: { id: "29:15fREhoUuf6vVCOuaJYVH-AB6QXXX", name: "MOD Administrator" } } ] }}
Note : ID and Name can be fetched from the activity as follows
from: {
id: '29:15fREhoUuf6vVCOuaJYVH-AB6QXXX',
name: 'MOD Administrator',
aadObjectId: 'XXXX'
}
Giving a reference that will help - mention-support-within-adaptive-cards-v12