Just-Released Windows 10 v21H1 Gets Its Own List of Known Issues Minutes After Public Release
Microsoft has started delivering Windows 10 May 2021 Update to devices running version 2004 or 20H2. The feature update is also available via ISO files that help you skip the line. However, the company has already reported two known issues affecting version 21H1. The good news is that both have mitigations available, which means no safeguard hold has been put in place (as yet).
Here is the current list of Windows 10 May 2021 Update known issues
1- A high-pitched noise might be heard when using 5.1 audio with certain settings (Tagged as Mitigated)
After installing  or later updates, 5.1 Dolby Digital audio may play containing a high-pitched noise or squeak in certain apps when using certain audio devices and Windows settings. Note This issue does not occur when stereo is used.
Workaround: To mitigate this issue, you can try one or more of the following:
- Streaming the video or audio in a web browser or different app, instead of the app affected by this issue.
- Enable Spatial sound settings by right clicking or long pressing on the volume icon in the notification area, selecting Spatial sound (Off) and selecting any of the available options.
The problem not only affects version 21H1 but also impacts Windows 10 version 20H2 and version 2004. The Windows maker said that it's working on a resolution and will provide an update in an upcoming release.
2- Automatic input of Furigana might not work as expected
When using the Microsoft Japanese Input Method Editor (IME) to enter Kanji characters in an app that automatically allow the input of Furigana characters, you might not get the correct Furigana characters and might need to enter them manually. Note for developers: Affected apps are using the ImmGetCompositionString function.
Workaround: To mitigate this issue, please follow the instructions in Revert to a previous version of an IME (Input Method Editor).
This issue also impacts version 2004, 20H2, and the latest 21H1 since all three share a common core operating system and an identical set of system files.
We will keep this list updated as Microsoft confirms other problems with this feature update.