Glad to hear you found a working configuration without having to revert to an outdated and non-standard IDE version.
You also have narrowed down the source of the problem considerably if you wanted to investigate further. The problem was caused by something that changed between Arduino AVR Boards 1.6.10 and 1.6.11. Both those versions use the same compiler toolchain version so you can eliminate that. You can see a list of the changes made between Arduino IDE 1.6.8 (which includes Arduino AVR Boards 1.6.10) and Arduino IDE 1.6.9 (which includes Arduino AVR Boards 1.6.11) here:
Unfortunately Arduino AVR Boards is part of the Arduino IDE repository so you find some irrelevant commits in there that are changes to the IDE code, not Arduino AVR Boards.