diff --git a/deps/graph-parser/src/logseq/graph_parser/block.cljs b/deps/graph-parser/src/logseq/graph_parser/block.cljs
index 3acd5b3a3b..1ed122bfa8 100644
--- a/deps/graph-parser/src/logseq/graph_parser/block.cljs
+++ b/deps/graph-parser/src/logseq/graph_parser/block.cljs
@@ -428,7 +428,12 @@
                                (get-in properties [:properties :id]))]
         ;; guard against non-string custom-ids
         (when-let [custom-id (and (string? custom-id) (string/trim custom-id))]
-          (some-> custom-id parse-uuid)))
+          ;; mldoc's Property_Drawer may include trailing content after the
+          ;; id value (e.g. when the block has content on subsequent lines).
+          ;; Take only the first line so parse-uuid can match the UUID.
+          ;; See https://github.com/logseq/og/issues/35
+          (let [custom-id (-> custom-id (string/split-lines) first string/trim)]
+            (some-> custom-id parse-uuid))))
       (d/squuid)))
 
 (defn get-page-refs-from-properties
diff --git a/src/main/frontend/util/property.cljs b/src/main/frontend/util/property.cljs
index e6d80da35f..46b8663e9a 100644
--- a/src/main/frontend/util/property.cljs
+++ b/src/main/frontend/util/property.cljs
@@ -231,6 +231,15 @@
    (when (string? content)
      (let [ast (content/get-ast content format)
            title? (content/has-title? content format)
+           ;; Whether the first AST node is a real heading (as opposed to
+           ;; Paragraph/Raw_Html/Hiccup which block-with-title? also matches).
+           ;; Only real headings should have the property inserted after the
+           ;; title line. For Paragraph/Raw_Html/Hiccup (e.g. HTML blocks),
+           ;; the property must go at the very first line so that mldoc can
+           ;; parse it as a Property_Drawer. Otherwise the property ends up on
+           ;; the second line and is never recognized.
+           ;; See https://github.com/logseq/og/issues/35
+           first-node-heading? (= "Heading" (ffirst (map first ast)))
            has-properties? (or (and title?
                                     (or (mldoc/properties? (second ast))
                                         (mldoc/properties? (second
@@ -304,7 +313,7 @@
                                   has-properties?
                                   (compose-lines)
 
-                                  title?
+                                  (and title? first-node-heading?)
                                   (cons (first lines) (cons new-property-s (rest lines)))
 
                                   :else