Error during delete the Sort set

i created new sort set in datastructure, where i set 2 entity fields, one ascending, second descending, then i deleted this sort set. After collapse and expand datastructure tree, Architect sent this error, which I confirmed, and all created datastructure disappeared. After deleting index.bin and restarting Architect, error disappeared and datastructure is in tree.

ver. 4988

edit: it happens every time after removal of anything

Error
Error occured while reading child nodes of node 'ArchitectTests\Data\Data Structures'.

Could not find object with id:8b2109a9-0a50-4ca0-af71-1b51caa02c75 in file: c:\Temp\ArchitectTests\ArchitectTests\DataStructure\Test1.origam
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Could not find object with id:8b2109a9-0a50-4ca0-af71-1b51caa02c75 in file: c:\Temp\ArchitectTests\ArchitectTests\DataStructure\Test1.origam
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 Stack trace
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   at Origam.DA.ObjectPersistence.Providers.OrigamXmlManager.GetCachedObject(Guid id, IPersistenceProvider provider)
   at Origam.DA.ObjectPersistence.Providers.OrigamXmlManager.LoadObject(Guid id, IPersistenceProvider provider, Boolean useCache)
   at Origam.DA.Service.FilePersistenceProvider.RetrieveInstance(PersistedObjectInfo persistedObjInfo, Boolean useCache)
   at Origam.DA.Service.FilePersistenceProvider.RetrieveListByParent(Guid id, ElementName elementName, Type type, Boolean useCache)
   at Origam.DA.Service.FilePersistenceProvider.RetrieveListByParent[T](Key primaryKey, String parentTableName, String childTableName, Boolean useCache)
   at Origam.Schema.AbstractSchemaItem.GetChildItems(AbstractSchemaItem parentItem)
   at Origam.Schema.AbstractSchemaItem.InitializeItemCache()
   at Origam.Schema.AbstractSchemaItem.get_ChildItems()
   at Origam.Schema.AbstractSchemaItem.ChildNodes()
   at Origam.Workbench.ExpressionBrowser.HasChildNodes(IBrowserNode node)
   at Origam.Workbench.ExpressionBrowser.LoadTreeRecursive(TreeNode parentNode)
   at Origam.Workbench.ExpressionBrowser.LoadTree(TreeNode parentNode)```