common_ground:
Yes, SpenceKonde ( DrAzzy ) is really great guy who maintain their cores seriously, and offten. I solved other Attiny(13) problems by adding new preprocessing rules in cores platform.txt, so i will declare solution for tiny13 when i do some other libs. issue correction.
I agree! The fixed version(1.0.6) of ATTinyCore and arduino-tiny-841 are now also available via Boards Manager: http://drazzy.com/package_drazzy.com_index.json