AdaptiveTextBlock text does not render correctly on iOS devices

Question

In my MSTeams Bot, I send messages to the users with buttons. I am using Adaptive Card and other adaptive controls for these messages. For Windows desktop and Android Teams app, these messages are rendered as required, But in iOS devices it doesnt.

This is a screenshot of the messages on windows desktop.

This is screenshot of the message on iPad.

These are the issues I have seen in iOS.

1. When words in the text of AdaptiveTextBlock are placed between "**" to make them highlighted the whole sentence is also getting bolder. the words which needs to be hightlighted are bolder than the other words.
2. If the text contains the mentioned username the hightlighting doesnt work at all. Sometimes the whole message is invisible.

Do I have to set any other properties of the textblock to get it rendered properly on the iOS or is this an issue with iOS Teams App.

Below is my code to create and send the card.

var entList = new List() { new Mention() { Mentioned = new ChannelAccount(id: turnContext.Activity.From.Id, name: turnContext.Activity.From.Name), Text = $"{turnContext.Activity.From.Name}", } };

                    var card = new AdaptiveCard("1.5");
                    var tblock = new AdaptiveTextBlock();
                    tblock.Text = "<at>"+ turnContext.Activity.From.Name + "</at> Hi! this is **bold text**";
                    tblock.Wrap = true;
                    card.Body.Add(tblock);

                    var act = MessageFactory.Text("");
                    act.Attachments.Add(new Attachment()
                    {
                        Content = card,
                        ContentType = AdaptiveCard.ContentType
                    });

                    var entities = new { entities = entList };
                    card.AdditionalProperties.Add("msteams", entities);

                    await turnContext.SendActivityAsync(act);