Prevent tables grid from losing columns

src/RolemasterDb.App/Components/Pages/Tables.razor

@@ -759,7 +759,12 @@
             selectedGroupKey = string.Empty;
         }
 
-        if (tableDetail.Columns.All(column => !string.Equals(column.Key, selectedColumnKey, StringComparison.OrdinalIgnoreCase)))
+        var matchingColumns = tableDetail.Columns
+            .Where(column => string.IsNullOrWhiteSpace(selectedColumnKey)
+                || string.Equals(column.Key, selectedColumnKey, StringComparison.OrdinalIgnoreCase))
+            .ToList();
+
+        if (matchingColumns.Count == 0)
         {
             selectedColumnKey = string.Empty;
         }

src/RolemasterDb.App/Components/Tables/TablesCanvas.razor

@@ -129,9 +129,11 @@
             cellIndex[(cell.RollBand, cell.GroupKey, cell.ColumnKey)] = cell;
         }
 
+        var columnsToDisplay = ResolveVisibleColumns();
+
         if (Detail.Groups.Count == 0)
         {
-            foreach (var column in Detail.Columns.Where(MatchesColumnFilter))
+            foreach (var column in columnsToDisplay)
             {
                 visibleColumns.Add(column);
                 displayColumns.Add((null, column.Key, column.Label));
@@ -139,12 +141,14 @@
         }
         else
         {
-            foreach (var group in Detail.Groups.Where(MatchesGroupFilter))
+            var groupsToDisplay = ResolveVisibleGroups();
+
+            foreach (var group in groupsToDisplay)
             {
                 visibleGroups.Add(group);
             }
 
-            foreach (var column in Detail.Columns.Where(MatchesColumnFilter))
+            foreach (var column in columnsToDisplay)
             {
                 visibleColumns.Add(column);
             }
@@ -173,6 +177,28 @@
         string.IsNullOrWhiteSpace(SelectedColumnKey)
         || string.Equals(column.Key, SelectedColumnKey, StringComparison.OrdinalIgnoreCase);
 
+    private IReadOnlyList<CriticalGroupReference> ResolveVisibleGroups()
+    {
+        var filteredGroups = Detail.Groups
+            .Where(MatchesGroupFilter)
+            .ToList();
+
+        return filteredGroups.Count > 0
+            ? filteredGroups
+            : Detail.Groups;
+    }
+
+    private IReadOnlyList<CriticalColumnReference> ResolveVisibleColumns()
+    {
+        var filteredColumns = Detail.Columns
+            .Where(MatchesColumnFilter)
+            .ToList();
+
+        return filteredColumns.Count > 0
+            ? filteredColumns
+            : Detail.Columns;
+    }
+
     private bool MatchesModeFilter(CriticalTableCellDetail cell) =>
         CurrentMode switch
         {