The staff attending to me casually told me they have most colors in stock (I assumed except the red one) but not all the sizes, and maybe that one staff might not actually know how the bands are actually selling. I am in located in Asia, and since tourists are not allowed in at the moment (usually the bulk of the people in the Apple Store are tourists buying tax-free), it might be a local thing.
He also told me that sport loops don't sell well too, and showed me the stock status with almost everything available marked with the green mark (in stock). I tend to ignore local band trends and I love the sport loops after trying them out, so that was quite surprising.