Garmin connect automatically recording exact same step count every day for past 3 weeks and saying I have achieved my step goal first thing in morning .

What does your watch say? Does it say that you achieved your step goal? If yes, then it is the watch that is the issue here. Have you restarted it? Does the step counter work?

Thanks for reply ! Watch saying the same . I have restarted it many times but was hoping to avoid having to factory reset . Step counter not working from what I can see as just registering same step count each day . 
calories also much lower than expected for runs which is also likely a sign that step count not working . 

You can look at the step widget in the watch and see what it says. If you move your arm up and down (like running motion) for at least 10 times it should start counting.

It doesn’t change at all . Exact same step count each day and doesn’t change with movement 

You could try to do the factory reset, but this is probably a case for Garmin Support: https://support.garmin.com/