Fix button system visual issue

osu.Game/Screens/Menu/Button.cs

@@ -63,6 +63,8 @@ public Button(string text, string sampleName, IconUsage symbol, Color4 colour, A
             {
                 box = new Container
                 {
+                    // box needs to be always present to ensure the button is always sized correctly for flow
+                    AlwaysPresent = true,
                     Masking = true,
                     MaskingSmoothness = 2,
                     EdgeEffect = new EdgeEffectParameters