diff --git a/pdl-live-react/src/view/masonry/MasonryCombo.tsx b/pdl-live-react/src/view/masonry/MasonryCombo.tsx
index 5b873dd2c..defa5ca90 100644
--- a/pdl-live-react/src/view/masonry/MasonryCombo.tsx
+++ b/pdl-live-react/src/view/masonry/MasonryCombo.tsx
@@ -117,12 +117,14 @@ export default function MasonryCombo({ value, setValue }: Props) {
   // special form of setModalContent for running a PDL program
   const run = useCallback<Runner>(
     async (runThisBlock, async = false, update) => {
-      if (!isNonScalarPdlBlock(block) || !isNonScalarPdlBlock(runThisBlock)) {
+      if (!isNonScalarPdlBlock(block)) {
         return
-      }
-      if (!runThisBlock) {
+      } else if (!runThisBlock) {
         runThisBlock = block
       }
+      if (!isNonScalarPdlBlock(runThisBlock)) {
+        return
+      }
 
       const [cmd, input, output] = (await invoke("replay_prep", {
         trace: JSON.stringify(runThisBlock, (k, v) =>