#+OPTIONS: html-preamble:"<p class='author'>Author: %a<br/>(%e)</p><p
class='date'>Date: %d</p><p><img src='./img/SemBSDD-Logo-400px.png'/></p>"

C-c happily says "Local setup has been refreshed"

But then C-c C-e h h complains: "org-export--parse-option-keyword: End of
file during parsing".
I don't see any problem in the string; evaluating it in *scratch* returns
it just fine.
But I think  org-export--parse-option-keyword uses some limited reader...