Just yesterday, Microsoft pushed out Windows 10 Insider build 17025 for PC to the Slow ring but turns out that might be all the Windows Insider action for the week. The Windows Insider team apparently has hit a bug in testing, and will not be pushing out any new Fast ring Windows 10 Redstone 4 Insider builds this week as a result.
#WindowsInsiders: no Fast ring release this week. We have hit a bug in testing where we sometimes green screen when connecting power.
— Dona Sarkar @ #MSIgnite prep (@donasarkar) November 2, 2017
According to Dona Sarkar, it looks as though the team is getting a green screen (which is the Insider version of the blue screen of death) when connecting power to some devices. This is definitely a very serious issue that needs to be attended to, as the last thing Insiders would want is a build that renders their PCs useless.
The last time a Fast ring build was released was just about a week ago with build 17025. So you Windows Insiders will just have to spend some more time focusing on bug smashing from the last release, and not downloading new builds.