Global Invalidation causes CommonAnimatedSwitcher to flicker after animation completes

The common animated switcher will currently flicker for one frame when its transition animation completes if global invalidation is enabled. This appears to be caused by a visibility change (HitTestInvisible -> SelfHitTestInvisible) which we perform to prevent interactions during the transition. The visibility change happens within an active timer, which may explain why it misbehaves compared to normal visibility invalidations.

1) Download attached widget and add it to viewport (created in 5.5)
2) Launch PIE in new editor window
3) Enable global invalidation (Slate.EnableGlobalInvalidation 1)
4) Click the button to cycle between pages
Note the flicker when the animation finishes (new page is fully faded in)
Flicker is caused by a Visibility Invalidation in  SCommonAnimatedSwitcher::UpdateTransition

SetVisibility(EVisibility::SelfHitTestInvisible);