On hover, I sometimes get documentation for a completely different thing than the identifier I hover over. The "different thing" is usually something that comes from stdlib such as > operator or as in the screenshot, where I hover over err_pos_range and get correct type but not doc.

(might be a merlin issue, but the last issue found with ocaml-lsp I raised in merlin repo turned out to be ocaml-lsp related, so creating the issue here)