[MythicMobs] Attack Speed as a Range on items does not work

I set up a static attack speed, it works (-0.6 = -60% = vanilla 1.6). However setting up a range does not.

For example:

    Attributes:
        MainHand:
            AttackSpeed: -0.60- -0.55 

is resulting in -5% attack speed

I also tried -0.60- -0.55, -0.60--0.55 -> result -5% static -0.60to-0.55 -> result in 100% static

I assume there is a defect in interpreting - as "minus" vs - as "to". Is there a different syntax for negative ranges I can use?