Hi, I tried installing RC2 (netboot) on my ASUS TP200SA yesterday and ran into a similar issue, os-prober hang during the install-grub phase. The thing here is that I'm neither using LVM nor any crypto, just the plain eMMC with a couple of partitions (see below).
I could successfully finish the installation by manually killing the os-prober processes (there were multiple running) and then trying the GRUB re-install again via the install menu. The second time it worked. After I finished the installation I decided to try again, restarted a fresh installation and same thing - os-prober would hang on the first attempt but finish without any issues after killing and re-trying. Not sure if this any useful info but I thought I'd mention it b/c I don't see any reports for plain, non-encrypted, non-LVM disks showing this issue. But maybe it's a completely different problem? FWIW: root@flexo:~# fdisk -l Disk /dev/mmcblk0: 29.1 GiB, 31268536320 bytes, 61071360 sectors Units: sectors of 1 * 512 = 512 bytes Sector size (logical/physical): 512 bytes / 512 bytes I/O size (minimum/optimal): 512 bytes / 512 bytes Disklabel type: gpt Disk identifier: 32DFD951-1036-41D1-A0A0-FA02557229F3 Device Start End Sectors Size Type /dev/mmcblk0p1 2048 4095 2048 1M BIOS boot /dev/mmcblk0p2 4096 395263 391168 191M EFI System /dev/mmcblk0p3 395264 5277695 4882432 2.3G Linux swap /dev/mmcblk0p4 5277696 5570559 292864 143M Linux filesystem /dev/mmcblk0p5 5570560 61069311 55498752 26.5G Linux filesystem Disk /dev/mmcblk0boot1: 4 MiB, 4194304 bytes, 8192 sectors Units: sectors of 1 * 512 = 512 bytes Sector size (logical/physical): 512 bytes / 512 bytes I/O size (minimum/optimal): 512 bytes / 512 bytes Disk /dev/mmcblk0boot0: 4 MiB, 4194304 bytes, 8192 sectors Units: sectors of 1 * 512 = 512 bytes Sector size (logical/physical): 512 bytes / 512 bytes I/O size (minimum/optimal): 512 bytes / 512 bytes Disk /dev/mmcblk1: 59.8 GiB, 64223182848 bytes, 125435904 sectors Units: sectors of 1 * 512 = 512 bytes Sector size (logical/physical): 512 bytes / 512 bytes I/O size (minimum/optimal): 512 bytes / 512 bytes Let me know if I can provide any other information. Cheers!