diff --git a/src/compile/mark/encode/nonposition.ts b/src/compile/mark/encode/nonposition.ts
index 3f2380d4d1..8ffe7b1ffa 100644
--- a/src/compile/mark/encode/nonposition.ts
+++ b/src/compile/mark/encode/nonposition.ts
@@ -1,6 +1,6 @@
 import type {SignalRef} from 'vega';
 import {NonPositionScaleChannel} from '../../../channel';
-import {Value} from '../../../channeldef';
+import {Value, isConditionalDef} from '../../../channeldef';
 import {VgEncodeChannel, VgEncodeEntry, VgValueRef} from '../../../vega.schema';
 import {getMarkPropOrConfig, signalOrValueRef} from '../../common';
 import {UnitModel} from '../../unit';
@@ -24,16 +24,22 @@ export function nonPosition(
   const {vgChannel} = opt;
   let {defaultRef, defaultValue} = opt;
 
+  const channelDef = encoding[channel];
+
   if (defaultRef === undefined) {
     // prettier-ignore
-    defaultValue ??= getMarkPropOrConfig(channel, markDef, config, {vgChannel, ignoreVgConfig: true});
+    defaultValue ??= getMarkPropOrConfig(channel, markDef, config, {
+      vgChannel,
+      // If there is no conditonal def, we ignore vgConfig so the output spec is concise.
+      // However, if there is a conditional def, we must include vgConfig so the default is respected.
+      ignoreVgConfig: !isConditionalDef(channelDef)
+    });
 
     if (defaultValue !== undefined) {
       defaultRef = signalOrValueRef(defaultValue);
     }
   }
 
-  const channelDef = encoding[channel];
   const commonProps = {
     markDef,
     config,