Is it possible to be responsive to Topical, but not Oral Minoxidil?

I've recently switched from Topical 5% Minoxidil foam to Oral Minoxidil 2.5 mg/day. I had stable hair in mid-scalp/crown for years using topical, but wanted to switch for convenience/healthier scalp. Noticed immediate thinning 1 month in and a lot more after 3 months at those two areas. Not seeing much regrowth. Is it possible to have steady success with topical but not responsive to oral?