Bug introduced in 9.0 or earlier and fixed in 11.0.0
CheckboxBar doesn't work with TrackedSymbols and a custom callback function.
Here's an example that doesn't work
x = {}
CheckboxBar[Dynamic[x, Print, TrackedSymbols :> {x}], {1, 2, 3}]
whereas this works
CheckboxBar[Dynamic[x, Print], {1, 2, 3}]
It took me a few hours to find this, as I usually use auxiliary functions that set TrackedSymbols systematically, as this is really necessary when the amount of dynamic user interface elements displayed at the same time gets big.
The question is why it doesn't work with TrackedSymbols although it's probably a bug.
TogglerBarhas a problem too. The symptoms are not exactly the same.TogglerBar[Dynamic[x, Print, TrackedSymbols :> {x}], {1, 2, 3}]gives 3 buttons but when you push them, it print nothing. – andre314 Feb 17 '16 at 21:05