ReactOS doesn't load FreeLDR after downtime at bootloader install step

This happens for me in VirtualBox. Not tested in other VMs or with real hardware by me.

Steps to reproduce:
1. Begin ReactOS installation and format partition in BTRFS;
2. Install ReactOS as usual, but wait around 15-20 seconds when setup asks to install a bootloader;
3. Continue a bootloader installation;
4. After reboot, VirtualBox VM fails with guru meditation. 

It happens often for me.

See this YouTube video for details. The main action begins at 1:30.

https://www.youtube.com/watch?v=OtF7_5FQ-vM

UPD: Doesn't happen with FAT