Been looking everywhere online, could only find references to Lion and Yosemite, with one unsourced page (macOS + Windows 10 + shared data partition) saying that all the old methods would no longer work.
I have a new 2017 Macbook Pro, with a 512 GB SSD. I wanted to run Windows on it (obviously). At first, I just ran the Bootcamp Assistant and everything went well. But then I decided that I wanted a shared exFAT partition between my MacOS Sierra and Windows 10 installs. I tried to repartition the Mac partition with Disk Utility, and ended up bricking the laptop. First Aid kept giving "Invalid number of allocation blocks" errors, and the laptop refused to boot.
I gave up and reinstalled Sierra via the Recovery Partition. However, when I try to rerun Bootcamp Assistant, it always gives a "Disk failed to be partitioned" error. I'm even unable to partition the main drive further with Disk Utility. I've done everything - clear PRAM, /sbin/fsck -fy, reinstall Sierra, even DiskWarrior. The laptop functions fine, but I find myself unable to create any new partition.
Moreover, every failed attempt nevertheless creates 64+8 GB of unformatted partitions, which corrupts the partition table. Each time this happens, I am unable to boot until going through recovery mode to fix it with Paragon's Hard Disk Manager.
How can I fix the system for bootcamp?