FIX: missing clause for parsing the xml of subselects with lists

src/caosdb/common/models.py

@@ -3855,6 +3855,8 @@ def _parse_single_xml_element(elem):
     elif elem.tag.lower() == "value":
         if len(elem) == 1 and elem[0].tag.lower() == "emptystring":
             return ""
+        elif len(elem) == 1 and elem[0].tag.lower() in classmap:
+            return _parse_single_xml_element(elem[0])
         elif elem.text is None or elem.text.strip() == "":
             return None