Gathering more in depth info now, but I've been testing along the same lines.
<=r11514 = works
>=r11520 = broken (tested as far as r11535)
This is without changing the firmware files (which I likely updated right from raspberry's github when the issue started, but I'm not sure)
Further, r11514 using the bootcode.bin, loader.bin, and start.elf included in r11535 also works.
For the sake of credit and completeness, I'm using http://openelec.thestateofme.com/
as the source for all OpenELEC files.