Span element inside a p element gets removed


I give the editor HTML content to parse it, for example (I placed span elements in 3 positions): <p>Hello this is a test</p><p>d <span keyID="#key09"> </span> a</p><p><span keyID="#key09"> </span></p><p>s<span keyID="#key09"> </span>v</p><p>a</p>

And the rendered result in editor looks like this (The question marks are removed span elements got removed ones): <p>Hello this is a test</p><p>d **?** a</p><p>**?**</p><p>s<span keyID="#key09"> </span>v</p><p>a</p>

as you can see the only one who is still remained is the one who got text around it (not even space it should be only text.) i don’t want anything to be removed.

What kind of node or mark in your schema are you expecting these to match to?