update - I tried all of the above solutions with no success - until I went into the "apps" section in my spotify account, removed the access granted to alexa, then I was able in the spotify app to re-enable the access, and now it works.
update - I tried all of the above solutions with no success - until I went into the "apps" section in my spotify account, removed the access granted to alexa, then I was able in the spotify app to re-enable the access, and now it works.