diff --git a/simpletuner/templates/trainer_dataloader_section.html b/simpletuner/templates/trainer_dataloader_section.html
index bb330364d..49dca3309 100644
--- a/simpletuner/templates/trainer_dataloader_section.html
+++ b/simpletuner/templates/trainer_dataloader_section.html
@@ -900,7 +900,7 @@
                 const trainer = Alpine.store('trainer');
                 if (trainer) {
                     if (typeof trainer.markDatasetsDirty === 'function') {
-                        trainer.markDatasetsDirty();
+                        trainer.markDatasetsDirty({ refresh: this.dataLoaderMode !== 'json' });
                     } else {
                         trainer.hasUnsavedChanges = true;
                     }
diff --git a/simpletuner/templates/trainer_htmx.html b/simpletuner/templates/trainer_htmx.html
index 735a5ade2..c489db66f 100644
--- a/simpletuner/templates/trainer_htmx.html
+++ b/simpletuner/templates/trainer_htmx.html
@@ -2074,9 +2074,12 @@
             const sanitized = this.prepareDatasetsForSave();
             this.dataLoaderJson = JSON.stringify(sanitized, null, 2);
         },
-        markDatasetsDirty() {
+        markDatasetsDirty(options = {}) {
+            const { refresh = true } = options || {};
             this.hasUnsavedChanges = true;
-            this.refreshDatasetsJson();
+            if (refresh && this.dataLoaderMode !== 'json') {
+                this.refreshDatasetsJson();
+            }
         },
         async loadCaptionFilters(force = false) {
             if (!force && Array.isArray(this.captionFilters) && this.captionFilters.length > 0) {