When trying to add a credit card to Garmin IQ, an error message appears that the security code is incorrect or has not been entered. Have tried with different cards, same results

Same here

I have the same issue when trying to perform the purchase / add the card via the Connect IQ App on Android. However, I was able to work around this by performing the purchase on a Desktop PC via a browser from https://apps.garmin.com/

same here

Same issue, here. Depressing that the original post is 5 months old and the same issue is still there.

Garmin has changed the app store, so one can't do that any more - they are forcing us onto the mobile app for everything! And this problem is still there, so I can't buy any watch faces or apps.

Seems like Garmin doesn't want our money - or is trying to kill the 3rd party apps market!

Got it! You have to go into the Connect app [not IQ] then into the Garmin Pay section, add a delivery address for each card, and then verify the card for ecommerce transactions.

You're right... good find and thanks for noting it down here. I had some cards already in Wallet for the GarminPay functionality with addresses, but had not seen the ecommerce pay toggle. Now toggled and can pay for IQ store stuff.

Interestingly I was trying to pay with my main card which is not on the GarminPay list.  I could add it to the Wallet, but there is no eCommerce payment toggle - it simply does not see it. It seems that Garmin have set up payments on IQ purely through GarminPay. Which is an interesting choice seeing the limited number of banks that support GarminPay (certainly in my country, the UK - I'm lucky that one of my accounts is in a bank on the list).

It seems that Garmin are still significantly limiting options for potential buyers from IQ a) through forced use of GarminPay, and b) through a really opaque system to use the thing!  I'm not sure if this is purposeful, or invalid assumption re GarminPay reach (outside the US possibly), but either way they are not helping third party developers. I can see why most of them use alternative payment sites now.