I only discovered it when I had 2 pilots PM me on center within one hour and what my reason was for deleting their TAS. I told them it was a mistake and AM the speed back in. I'm sure most pilots wouldn't notice or care. I was just bring it up to use caution.
For some reason whenever I do a route AM posted above, It deletes the filed TAS and somehow the pilots notice to make things worse. Changes the filed TAS to 000.