Amazon now has a standalone website for its Amazon Music streaming service, https://music.amazon.com/home. Within it, there are unique URL formats for artists and releases that under the current URL cleanup scheme cannot be entered as-is.
As this site only covers streaming audio, the links should autoselect to "stream for free" (yes, I know this is a little misleading; Amazon Music is a subscription service, i.e. not free).
Example artist page: https://music.amazon.com/artists/B000QKDMIG
Example release page: https://music.amazon.com/albums/B00138H5YM