Sorry for the late reply! This is… somewhere in the weird gray area between user error and implementation error! It was working as designed, but the design had a subtle non-obvious non-optimality.
If you moused over the # icon, it used to say “track number in the task; either the last number or the number in the first regex group” and since your regex has a group, it was looking in there for the number. This is useful because it lets you beemind multiple numbers from the same intention. I used this for tracking calories, carbs, protein, awhile back:
But this seems pretty obviously dumb, so I’ve changed it so that it only tries using the user’s regex to find the number iff the user’s regex contains
(\d+) somewhere. It doesn’t do this in the smartest way atm*, but I think it’ll suffice for all current implementations. And your thing should work now!
(*it uses the first regex group result that successfully parses as a number.)