Public Domain Derivatives Being Denied

I keep running into a problem with distributors other than Amazon (and YouTube) and refusing to distribute works that are derived from public domain works, including FAIRY TALES! Most recently, I am having to remove about a quarter of my audiobooks from Voices by Inaudio but I have also had trouble with Draft2Digital (although to a lesser extent).

Has anyone else run into this problem and were you able to eventually get those books distributed? It seems completely ridiculous that we are basically being denied the ability to sell books that are perfectly legal to write because “copyright law is complicated” (that’s the reason they give).