Here's what's fixed, improved, and still broken in Windows 10 build 19577

It's been two weeks since we last got a new Windows 10 build in the Fast ring, and Microsoft missed the usual Wednesday schedule for its weekly build of Windows 10 for Insiders in the Fast ring, but a new build is still making its way to Insiders today. Build 19577 includes a new icon for Windows Security and some other additions, but it also comes with the usual list of fixes, improvements, and known issues.

Starting with what's been improved:

• Following up on our post about the new Cortana app, we wanted to let you know that in addition to timers and instant answers, which lit up last month, assistant conversations are now online. Some examples to try are “tell me a dad joke”, “tell me a bedtime story”, or “rock, paper, scissors.” We appreciate your patience while we worked on this. This is a server-side change, however we’re noting it here for awareness.
• We’ve updated the behavior of Advanced startup (Settings > Update & Security > Recovery > Advanced startup “Restart now”) to enable some Ease of Access features to work properly. For example, previously, if the narrator feature was enabled prior to launching Advanced startup, it would stop working. Now, Advanced startup will reboot directly into the Windows Recovery Environment.
• While the Vietnamese alphabet doesn’t include the Latin letters F, J, W, or Z, based on feedback we’re updating the grouping in the Start menu’s all app’s list to account for these letters when using this display language, so that apps like Windows PowerShell are included in the expected group.

This time around, Microsoft is also listing fixes separately from general improvements, and the list is pretty long:

• We fixed an issue where input would stop working in some places if clipboard history (WIN + V) was dismissed without pasting anything.
• We fixed an issue resulting in extra characters in the message in File Explorer when no files were listed yet in Recent Files.
• We fixed an issue where, when setting up Windows Hello while using the Arabic display language, the box tracking progress of setup wouldn’t line up with your face.
• We fixed an issue where preferred SafeSearch settings (Settings > Search > Permissions & History) were no longer persisting upgrade.
• We fixed an issue which caused the microphone to sometimes not work on certain devices from Builds 19559 to 19569. If you continue seeing issues with your microphone, please file a problem report in Feedback Hub with “recreate my problem” logs.
• We fixed an issue impacting Explorer.exe reliability when navigating in File Explorer for some Insiders.
• We fixed an issue where using Restart Manager API to restart explorer.exe would result in all open UWP apps being closed as well.
• We fixed an issue that could result in the DWM crashing when inking on your PC.
• We fixed an issue that could result in Outlook crashing if you typed too many characters into the To field using the Korean IME.
• We fixed an issue where, when using Storage Sense to clean up Windows.old, it might not be totally removed.
• We fixed an issue that could result in Settings hanging when accessing Windows Update Settings.
• We fixed an issue where the Family & Other Accounts page wouldn’t finish loading for some Insiders.
• We fixed an issue resulting in the system potentially bugchecking upon toggling Bluetooth ON and OFF after waking back from sleep.
• We fixed an issue for local account users where, until rebooting, night light would no longer work after attaching your Microsoft account.
• We fixed an issue resulting in the machine not rebooting and kicking off the scan when you selected Microsoft Defender Offline Scan in Windows Security.
• We fixed an issue resulting in Windows Update failing with error 0x80070002 for some users.
• We fixed a high hitting DWM crash that some Insiders were experiencing.

Even with all those fixes, there are a few known issues to be aware of:

• BattlEye and Microsoft have found incompatibility issues due to changes in the operating system between some Insider Preview builds and certain versions of BattlEye anti-cheat software. To safeguard Insiders who might have these versions installed on their PC, we have applied a compatibility hold on these devices from being offered affected builds of Windows Insider Preview. See this article for details.
• We are aware Narrator and NVDA users that seek the latest release of Microsoft Edge based on Chromium may experience some difficulty when navigating and reading certain web content. Narrator, NVDA and the Edge teams are aware of these issues. Users of legacy Microsoft Edge will not be affected. NVAccess has released a NVDA 2019.3 that resolves the known issue with Edge.
• We’re looking into reports of the update process hanging for extended periods of time when attempting to install a new build.
• We’re investigating reports that some Insiders are unable to update to newer builds with error 0x8007042b.
• The Documents section under Privacy has a broken icon (just a rectangle).
• When you upgrade with certain languages, like Japanese, the “Installing Windows X%” page isn’t rendering the text correctly (only boxes are displayed).
• The cloud recovery option for Reset this PC isn’t working on this build. Please use the local reinstall option when performing Reset this PC.
• When trying to use Win + PrtScn to capture a screenshot, the image is not saved to the Screenshots directory. For now, you’ll need to use one of the other options for taking screenshots, such as WIN + Shift + S.
• We’re looking into reports where, when running corruption repair (DISM), the process will stop at 84.9%.
• Notifications sometimes have the wrong actions associated with them (for example, a reply box or various buttons).

As Fast ring builds are no longer targeting a specific Windows 10 feature update, there's technically no guarantee that the features and improvements in this build will make their way to the general public anytime soon.