diff --git a/python_package/src/onlinemid/utils/image_plotting.py b/python_package/src/onlinemid/utils/image_plotting.py
index a2fe4824697bdba2b359a6f04966bea9fa8e68dc..9f8abe4b233cd1a26e3d584ebfeab53325306114 100644
--- a/python_package/src/onlinemid/utils/image_plotting.py
+++ b/python_package/src/onlinemid/utils/image_plotting.py
@@ -124,6 +124,7 @@ class DataToPlotToHash():
         basenode = hash_key
     
         res = Schema()
+
         (
             NODE_ELEMENT(res)
             .key(basenode)
@@ -140,6 +141,8 @@ class DataToPlotToHash():
             .key(f"{basenode}.update_interval")
             .displayedName('update interval')
             .description('update interval')
+            .assignmentOptional()
+            .defaultValue("")
             .commit(),
 
         )