diff --git a/src/libs/ReportUtils.ts b/src/libs/ReportUtils.ts
index 82aebd044a8f..d6a76162be0f 100644
--- a/src/libs/ReportUtils.ts
+++ b/src/libs/ReportUtils.ts
@@ -7406,8 +7406,8 @@ function getWorkspaceChats(policyID: string, accountIDs: number[], reports: Onyx
  *
  * @param policyID - the workspace ID to get all associated reports
  */
-function getAllWorkspaceReports(policyID: string): Array<OnyxEntry<Report>> {
-    return Object.values(allReports ?? {}).filter((report) => (report?.policyID ?? '-1') === policyID);
+function getAllWorkspaceReports(policyID: string | undefined): Array<OnyxEntry<Report>> {
+    return Object.values(allReports ?? {}).filter((report) => report?.policyID === policyID);
 }
 
 /**
diff --git a/src/libs/TransactionUtils/index.ts b/src/libs/TransactionUtils/index.ts
index 1aa5f5fe101e..2708b32246be 100644
--- a/src/libs/TransactionUtils/index.ts
+++ b/src/libs/TransactionUtils/index.ts
@@ -1244,11 +1244,10 @@ function compareDuplicateTransactionFields(
     return {keep, change};
 }
 
-function getTransactionID(threadReportID: string | undefined): string | undefined {
+function getTransactionID(threadReportID?: string): string | undefined {
     if (!threadReportID) {
         return;
     }
-
     const report = allReports?.[`${ONYXKEYS.COLLECTION.REPORT}${threadReportID}`];
     const parentReportAction = ReportUtils.isThread(report) ? ReportActionsUtils.getReportAction(report.parentReportID, report.parentReportActionID) : undefined;
     const IOUTransactionID = ReportActionsUtils.isMoneyRequestAction(parentReportAction) ? ReportActionsUtils.getOriginalMessage(parentReportAction)?.IOUTransactionID : undefined;
diff --git a/src/libs/actions/PersonalDetails.ts b/src/libs/actions/PersonalDetails.ts
index 94a9dc95e846..e0e739b56e86 100644
--- a/src/libs/actions/PersonalDetails.ts
+++ b/src/libs/actions/PersonalDetails.ts
@@ -37,7 +37,7 @@ Onyx.connect({
     key: ONYXKEYS.SESSION,
     callback: (val) => {
         currentUserEmail = val?.email ?? '';
-        currentUserAccountID = val?.accountID ?? -1;
+        currentUserAccountID = val?.accountID ?? CONST.DEFAULT_NUMBER_ID;
     },
 });
 
@@ -121,20 +121,36 @@ function updateDisplayName(firstName: string, lastName: string) {
 
 function updateLegalName(legalFirstName: string, legalLastName: string) {
     const parameters: UpdateLegalNameParams = {legalFirstName, legalLastName};
-
-    API.write(WRITE_COMMANDS.UPDATE_LEGAL_NAME, parameters, {
-        optimisticData: [
-            {
-                onyxMethod: Onyx.METHOD.MERGE,
-                key: ONYXKEYS.PRIVATE_PERSONAL_DETAILS,
-                value: {
-                    legalFirstName,
-                    legalLastName,
+    const optimisticData: OnyxUpdate[] = [
+        {
+            onyxMethod: Onyx.METHOD.MERGE,
+            key: ONYXKEYS.PRIVATE_PERSONAL_DETAILS,
+            value: {
+                legalFirstName,
+                legalLastName,
+            },
+        },
+    ];
+    // In case the user does not have a display name, we will update the display name based on the legal name
+    if (!allPersonalDetails?.[currentUserAccountID]?.firstName && !allPersonalDetails?.[currentUserAccountID]?.lastName) {
+        optimisticData.push({
+            onyxMethod: Onyx.METHOD.MERGE,
+            key: ONYXKEYS.PERSONAL_DETAILS_LIST,
+            value: {
+                [currentUserAccountID]: {
+                    displayName: PersonalDetailsUtils.createDisplayName(currentUserEmail ?? '', {
+                        firstName: legalFirstName,
+                        lastName: legalLastName,
+                    }),
                 },
+                firstName: legalFirstName,
+                lastName: legalLastName,
             },
-        ],
+        });
+    }
+    API.write(WRITE_COMMANDS.UPDATE_LEGAL_NAME, parameters, {
+        optimisticData,
     });
-
     Navigation.goBack();
 }