diff --git a/laf-cloud/functions/jungleTreasure.ts b/laf-cloud/functions/jungleTreasure.ts
index 133fb3c..72d38cf 100644
--- a/laf-cloud/functions/jungleTreasure.ts
+++ b/laf-cloud/functions/jungleTreasure.ts
@@ -165,7 +165,8 @@ async function settleExpiredRewards(
     [USER_STATE_FIELD]: storedStateValue,
   }).update({
     [USER_STATE_FIELD]: JungleConfig.serializeJungleState(settlement.state),
-    [PENDING_SETTLEMENT_FIELD]: pendingSettlement,
+    // 整体替换，避免 Laf 展开子字段后无法写入原值为 null 的结算记录。
+    [PENDING_SETTLEMENT_FIELD]: db.command.set(pendingSettlement),
     ...balances,
     timestamp: now,
   });