Bootcamp - Stuck on "Partitioning Disk..." When attempting to add a Windows 10 (April 2018, build 1803) partition to my 2019 iMac, I get stuck on "Partitioning disk..." perpetually. 

When I look at Disk Utility, the OSXRESERVED and BOOTCAMP partitions appear:



My iMac is running the latest stable release of macOS, 10.14.5 (18F132). Is there a known bug/solution to this problem?
Apple released a patch for my issue here: https://support.apple.com/kb/DL2007