After Windows Insiders were waiting for a new build, "Chief Ninja Cat" Dona Sarkar confirmed today that there will be no new builds this week, or even on Monday. When asked, she confirmed that this not only includes the Fast ring, but also those that chose to Skip Ahead (for Redstone 4 builds). Since Microsoft does tend to release Windows 10 Mobile builds after saying that nothing is coming for the Fast ring, it's worth noting that Dona confirmed that this does apply to phones as well.
It's an odd time for there to be a show-stopping bug in Windows 10, with the Fall Creators Update slated to be released on October 17. The firm is now only working on fixes and stability improvements for the OS before it reaches RTM, rather than adding features. This is normally the point in which builds are arriving more frequently, rather than missing a couple of weeks due to a critical bug.
Still, whatever the issue is, it seems to affect a broad range of versions, as those that chose to Skip Ahead aren't going to get anything, and those Insiders are already on Redstone 4, the codename for the feature update that's coming after the Fall Creators Update. Windows 10 Mobile users are on feature2, a development branch that's completely separate from Redstone 3.
No matter what the reason is, if you're hungry for a new Windows 10 build, you'll have to wait until at least Tuesday.