diff --git a/business/istio_config.go b/business/istio_config.go
index 531094ca16..3f8bd7be8e 100644
--- a/business/istio_config.go
+++ b/business/istio_config.go
@@ -161,7 +161,7 @@ func (in *IstioConfigService) GetIstioConfigListForNamespace(ctx context.Context
 	if _, err := in.businessLayer.Namespace.GetClusterNamespace(ctx, namespace, cluster); err != nil {
 		// Check if the namespace exists on the cluster in multi-cluster mode.
 		// TODO: Remove this once other business methods stop looping over all clusters.
-		if api_errors.IsNotFound(err) && len(in.userClients) > 1 {
+		if (api_errors.IsNotFound(err) || api_errors.IsForbidden(err)) && len(in.userClients) > 1 {
 			return &models.IstioConfigList{}, nil
 		}
 		return nil, err
diff --git a/business/namespaces.go b/business/namespaces.go
index f5899efaa8..8b212bcc1a 100644
--- a/business/namespaces.go
+++ b/business/namespaces.go
@@ -598,7 +598,10 @@ func (in *NamespaceService) GetClusterNamespace(ctx context.Context, namespace s
 	}
 
 	// Refresh namespace in cache since we've just fetched it from the API.
-	in.kialiCache.SetNamespace(client.GetToken(), result)
+	if _, err := in.GetClusterNamespaces(ctx, cluster); err != nil {
+		log.Errorf("Unable to refresh cache for cluster [%s]: %s", cluster, err)
+	}
+
 	return &result, nil
 }
 
@@ -634,7 +637,11 @@ func (in *NamespaceService) UpdateNamespace(ctx context.Context, namespace strin
 	kubeCache.Refresh(namespace)
 	in.kialiCache.RefreshTokenNamespaces(cluster)
 
-	// Call GetNamespace to update the caching
+	// Call GetClusterNamespaces to update the cache for this cluster.
+	if _, err := in.GetClusterNamespaces(ctx, cluster); err != nil {
+		return nil, err
+	}
+
 	return in.GetClusterNamespace(ctx, namespace, cluster)
 }
 
diff --git a/business/services.go b/business/services.go
index 74f7aa1dd6..3b58f34506 100644
--- a/business/services.go
+++ b/business/services.go
@@ -668,7 +668,6 @@ func (in *SvcService) UpdateService(ctx context.Context, cluster, namespace, ser
 		return nil, err
 	}
 	kubeCache.Refresh(namespace)
-	in.kialiCache.RefreshTokenNamespaces(cluster)
 
 	// After the update we fetch the whole workload
 	return in.GetServiceDetails(ctx, cluster, namespace, service, interval, queryTime)
diff --git a/handlers/apps.go b/handlers/apps.go
index 5949f72ade..80cb284197 100644
--- a/handlers/apps.go
+++ b/handlers/apps.go
@@ -6,6 +6,7 @@ import (
 	"strings"
 
 	"github.com/gorilla/mux"
+	"golang.org/x/exp/slices"
 
 	"github.com/kiali/kiali/business"
 	"github.com/kiali/kiali/models"
@@ -48,23 +49,27 @@ func (p *appParams) extract(r *http.Request) {
 // ClustersApps is the API handler to fetch all the apps to be displayed, related to a single cluster
 func ClustersApps(w http.ResponseWriter, r *http.Request) {
 	query := r.URL.Query()
-	namespaces := query.Get("namespaces") // csl of namespaces
-	nss := []string{}
-	if len(namespaces) > 0 {
-		nss = strings.Split(namespaces, ",")
-	}
+	namespacesQueryParam := query.Get("namespaces") // csl of namespaces
 	p := appParams{}
 	p.extract(r)
 
-	// Get business layer
 	businessLayer, err := getBusiness(r)
 	if err != nil {
 		RespondWithError(w, http.StatusInternalServerError, "Apps initialization error: "+err.Error())
 		return
 	}
-	if len(nss) == 0 {
-		loadedNamespaces, _ := businessLayer.Namespace.GetClusterNamespaces(r.Context(), p.ClusterName)
-		for _, ns := range loadedNamespaces {
+
+	nss := []string{}
+	namespacesFromQueryParams := strings.Split(namespacesQueryParam, ",")
+	loadedNamespaces, _ := businessLayer.Namespace.GetClusterNamespaces(r.Context(), p.ClusterName)
+	for _, ns := range loadedNamespaces {
+		// If namespaces have been provided in the query, further filter the results to only include those namespaces.
+		if len(namespacesQueryParam) > 0 {
+			if slices.Contains(namespacesFromQueryParams, ns.Name) {
+				nss = append(nss, ns.Name)
+			}
+		} else {
+			// Otherwise no namespaces have been provided in the query params, so include all namespaces the user has access to.
 			nss = append(nss, ns.Name)
 		}
 	}
@@ -75,8 +80,10 @@ func ClustersApps(w http.ResponseWriter, r *http.Request) {
 	}
 
 	for _, ns := range nss {
-		criteria := business.AppCriteria{Cluster: p.ClusterName, Namespace: ns, IncludeIstioResources: p.IncludeIstioResources,
-			IncludeHealth: p.IncludeHealth, RateInterval: p.RateInterval, QueryTime: p.QueryTime}
+		criteria := business.AppCriteria{
+			Cluster: p.ClusterName, Namespace: ns, IncludeIstioResources: p.IncludeIstioResources,
+			IncludeHealth: p.IncludeHealth, RateInterval: p.RateInterval, QueryTime: p.QueryTime,
+		}
 
 		if p.IncludeHealth {
 			rateInterval, err := adjustRateInterval(r.Context(), businessLayer, ns, p.RateInterval, p.QueryTime, p.ClusterName)
@@ -104,8 +111,10 @@ func AppDetails(w http.ResponseWriter, r *http.Request) {
 	p := appParams{}
 	p.extract(r)
 
-	criteria := business.AppCriteria{Namespace: p.Namespace, AppName: p.AppName, IncludeIstioResources: true, IncludeHealth: p.IncludeHealth,
-		RateInterval: p.RateInterval, QueryTime: p.QueryTime, Cluster: p.ClusterName}
+	criteria := business.AppCriteria{
+		Namespace: p.Namespace, AppName: p.AppName, IncludeIstioResources: true, IncludeHealth: p.IncludeHealth,
+		RateInterval: p.RateInterval, QueryTime: p.QueryTime, Cluster: p.ClusterName,
+	}
 
 	// Get business layer
 	business, err := getBusiness(r)