Operating system: Windows 10 64
Graphics card: 2080 ti x 4
Broken: 2.80-2.91 Alpha Daily Build Sept 4th 2020
Shape Key Editor name filtering search function does not filter or have any effect shape keys. Reproducible 100% of the time with any Blender version at least since January 2020.
The filter doesn't do anything regardless of the string used. On character figures with a couple hundred shape keys it becomes a bit of an issue.