May 11, 2021—KB5003169 (OS Build 18363.1556) (microsoft.com) appears to have fixed the issue.
- Addresses an issue that might cause scroll bar controls to appear blank on the screen and not function. This issue affects 32-bit applications running on 64-bit Windows 10 (WOW64) that create scroll bars using a superclass of the USER32.DLL SCROLLBAR window class. This issue also affects HScrollBar and VScrollBarcontrols and classes derived from System.Windows.Forms.ScrollBar. A memory usage increase of up to 4 GB might occur in 64-bit applications when you create a scroll bar control.