Garmin Connect Badges Not Being Awarded

You need to record the activity with a Garmin device. Manually entered and imported activities typically do not count for most badges, (though some imported applications are able to mimick the required format, and can bypass that limitation).

I gained the 10 mile & 20 mile Indoor Badges on Zwift?

These activities are NOT Manually entered or Imported by me, they are Automatically uploaded from Zwift.

10 mile on 1st September 2020.

20 mile on 13th July 2020.

so why not 50 km Badge?

Here is 20 mile link connect.garmin.com/.../5230233666 and Snapshot of Badge as evidence.

here is 10 mile link connect.garmin.com/.../5470881189 and Snapshot of Badge as evidence.

These activities are NOT Manually entered or Imported by me, they are Automatically uploaded from Zwift.

It does not matter whether they are imported manually or automatically. The are still imported, and not registered by a Garmin device, as they should be. Read about the badges requirements in the document Garmin Connect Badge Achievements. In the chapter "Are there any additional requirements that I should know about to earn a badge?", it is written clearly:

• Qualifying activities must be recorded using a Garmin device.

I don't dispute what you state, however, I have actually been given 7 Badges & associated points from activities on ZWIFT.

None of which were recorded on a Garmin Device.

Zwift uploads activities directly to Garmin Connect Website as I have linked both my Garmin & Zwift accounts.

This is merely a statement of fact, as can be seen from example below.

Yes, it looks odd. Maybe Garmin requires a Garmin device for the 50 km badge. It would be strange when it works with Zwift for 10 and 20 miles, but who knows? We can't see the algorithms and rules that decides whether or not an activity should be awarded with a badge. We can only work with what we read and experience.

If I was you I would export the FIT file and change the device to a Garmin device using the Device Changer here: https://www.fitfiletools.com and see if that helps.

A side note: You will get all three badges (10 and 20 miles and 50 km) with just one 50 km ride. I believe there is something wrong with the evaluation for these badges so all three can be awarded for the same ride. I thought they had fixed that so I did a trainer ride yesterday for 50 km and after that started a new ride to get the 10 miles badge, but during the last ride I saw that I got all three badges for the first ride so I quit after 10 km :-)

From what I can tell after way too little research, Garmin stopped allowing Zwift workouts count toward badges shortly after their contract between Tacx, a Garmin company and Zwift was over, and Zwift signed a new contract with Wahoo, Garmin's main competitor. Garmin decided to act like children and remove the feature, not hurting Zwift at all, only hurting their loyal customers like you and me. Sad that this was their decision, but sadly we must deal with large corporations acting like babies.