I didn't recall reading anything about only using a HSS (High Speed Tool Steel) tap for this type operation. I would never use a HF tap because it's probably carbon steel which is brittle and or sub par quality. I've done this for forty years and it can be done but I don't remember what you said you were tapping into. Or were you hand tapping or machine, single job or multiple? Anyway, if it is mild steel, aluminum, cast iron or other softer metals you can do it but obviously tap with a good HSS spiral pointed gun tap first. Then clean out hole 100% and hand tap (with oil/ coolant) the hole so you can feel the tap cut or not. If not cutting try something else. Tapping into a blind hole is problematic for the untrained. It's easy to break one off if you don't do everything correctly.