Thanks Jason.
I don’t know much about the mechanics of RSS, but it does seem that there’s a break in the process somewhere.
If I look at the raw RSS from this link (one example from my site, as I have it embedded), then it looks like all the links in the feed as served to Firefox do include the affiliate code:
https://www.amazon.com/gp/rss/bestsellers/digital-text/154606011/ref=zg_bs_154606011_rsslink&tag=kindlekitten-20
I’ve also checked this through Thunderbird, and all the links work.
Testing it with Feedroll – I see the same issue, i.e. that the code is not passed through:
https://www.feedroll.com/rssviewer/preview.php?src=http%3A%2F%2Fwww.amazon.com%2Fgp%2Frss%2Fbestsellers%2Fdigital-text%2F154606011%2Fref%3Dzg_bs_154606011_rsslink%26tag%3Dkindlekitten-20&targ=n&utf=y&css=
Interestingly, looking at a page on my site which does use this, I notice that the affilliate link does come through on some of the ‘site level’ Amazon links, but not the ‘Product level’:
https://kindlekitten.com/bestsellers/
On the above page, see any of the “Best Sellers in Kindle eBooks” links – they have the ‘kindlekitten-20’ tag embedded.
Could this be something as simple as the treatment of the ‘&’ character in the URL?
I did consider the template option, but I’m targeting multiple countries, and it looks like the is a maximum of 3 templates available.