There’s got to be some patch/update that either Linux or Microsoft, or both, pushed that now causes this problem. Just a couple of months ago everything worked fine, now, phffft, nothing.
In the past couple months a windows update prevents windows 10 from accessing the Homegroup top level harddrive shares on windows 7/8. However, a FOLDER that is shared that is on the harddrive can still be shared. Perhaps you should try sharing a FOLDER not at the top level harddrive to see if that can indeed be shared i.e. D: can not be shared, but D:\FOLDER , FOLDER can be shared.