Some problems with the regexes in the .tmLanguage. I tried to fix these myself but I couldn't manage 40 lines long regexes.

For example this works

**asd qwe**

and this doesn't

**asd
qwe**

And also lists are broken. You couldn't notice this with you scheme but if you have a scheme that applies styles to the list number/bullets you will see that only the first number/bullet is recognized as such and the rest doesn't get any styling. This used to work with the built-in markdown package. It also works with the Knockdown package although the regex for lists seem the same. For the last point you can use my package https://github.com/bobef/ColorSchemeEditor-ST2 for debugging as it shows shows the class for the element under the cursor in the status bar. Regards.