Ran into this exact issue when ordering hardware kits last month. The mobile app UI is notoriously buggy for group orders. I found that the invite button usually fails to load on certain Prime versions. Switching to a desktop browser fixed it immediately for me. The shareable link generated right in the cart summary there. It is not a business only feature, just poor app optimization.

Just caught up with the thread and unfortunately, I have to agree that the feature has become a real headache lately. I tried organizing a massive supply run for a community event a few months back using the group tool and it was a total disaster because the UI kept hiding the invite link for half my team. It really isnt as good as it used to be. Quick question though to see if I can help further: are you accessing the site through the US domain or are you on one of the international storefronts? The feature set changes depending on the region. Here is what I found while trying to keep costs down:

• The group cart often ignores individual clip and save coupons which can really hike up the price for snacks.
• Tracking who owes what is a nightmare because the final invoice doesnt always break down the taxes per person correctly.
• I usually give up on the official button and just use a shared shopping list instead since it is way more reliable for seeing what everyone wants without the glitchy invite system. It is honestly disappointing how much they have buried these features for standard Prime users.

Re: "Ran into this exact issue when ordering hardware..." - yeah the mobile app is definitely buggy with those API calls. Stick to the desktop version because the link generation is way more stable there. If that fails, using share amazon canada cart is a solid workaround for syncing lists without a business account. Just double-check your total since group orders sometimes mess with individual lightning deals or coupons.