Not a bug. Due to the order of how continuous effects are applied, Ashaya will always win out over any "lose abilitities" effects.

Ashaya changes the types of permanents, and thus starts applying in layer 4. Ability losing applies in layer 6. Additionally, once an effect starts to apply, it gets to apply fully, even if parts of it happen after the ability generating it is removed (613.6).

The same (non)issue applies to Kaito, Kudo, Ygra, and many other type changing cards. Ability losing is not an answer to them, it cannot shut them down.

All of the above also goes for color changing effects by the way, which happens in layer 5.