Fix lifetime override not working

osu.Game.Rulesets.Mania/Objects/Drawables/DrawableManiaHitObject.cs

@@ -13,11 +13,6 @@ namespace osu.Game.Rulesets.Mania.Objects.Drawables
 {
     public abstract class DrawableManiaHitObject : DrawableHitObject<ManiaHitObject>
     {
-        /// <summary>
-        /// Whether this <see cref="DrawableManiaHitObject"/> should always remain alive.
-        /// </summary>
-        internal bool AlwaysAlive;
-
         /// <summary>
         /// The <see cref="ManiaAction"/> which causes this <see cref="DrawableManiaHitObject{TObject}"/> to be hit.
         /// </summary>
@@ -54,7 +49,62 @@ namespace osu.Game.Rulesets.Mania.Objects.Drawables
             Direction.BindValueChanged(OnDirectionChanged, true);
         }
 
-        protected override bool ShouldBeAlive => AlwaysAlive || base.ShouldBeAlive;
+        private double computedLifetimeStart;
+
+        public override double LifetimeStart
+        {
+            get => base.LifetimeStart;
+            set
+            {
+                computedLifetimeStart = value;
+
+                if (!AlwaysAlive)
+                    base.LifetimeStart = value;
+            }
+        }
+
+        private double computedLifetimeEnd;
+
+        public override double LifetimeEnd
+        {
+            get => base.LifetimeEnd;
+            set
+            {
+                computedLifetimeEnd = value;
+
+                if (!AlwaysAlive)
+                    base.LifetimeEnd = value;
+            }
+        }
+
+        private bool alwaysAlive;
+
+        /// <summary>
+        /// Whether this <see cref="DrawableManiaHitObject"/> should always remain alive.
+        /// </summary>
+        internal bool AlwaysAlive
+        {
+            get => alwaysAlive;
+            set
+            {
+                if (alwaysAlive == value)
+                    return;
+
+                alwaysAlive = value;
+
+                if (value)
+                {
+                    // Set the base lifetimes directly, to avoid mangling the computed lifetimes
+                    base.LifetimeStart = double.MinValue;
+                    base.LifetimeEnd = double.MaxValue;
+                }
+                else
+                {
+                    LifetimeStart = computedLifetimeStart;
+                    LifetimeEnd = computedLifetimeEnd;
+                }
+            }
+        }
 
         protected virtual void OnDirectionChanged(ValueChangedEvent<ScrollingDirection> e)
         {