Preview LSP snippets?

[shyun3]

I thought that hovering over an LSP snippet menu entry would show a preview of that snippet but that no longer seems to be occurring for me:

Expansion still works fine though. To contrast, here's a result with cmp-nvim-ultisnips:

I expected a similar preview window to pop-up with LSP snippets. Have there been any breaking changes to this behavior?

[DOD-101]

For me, this is happening in particular with rust_analyzer. Although only on newer version and only for functions and macros.