We can see that it is 66 characters (33 bytes) long!!?! 
Private keys are only supposed to be 64 characters (32 bytes) of hex!
Private keys are only supposed to be 64 characters (32 bytes) of hex!If we delete the leading 00 we end up with 32 bytes, which looks like a correct size, still Ian Coleman's website doesn't recognize it.
On the other hand BouncyCastle.Crypto.dll 1.8.15362.1 has no problem with it.