In Adventurers League play, it is possible to find a "Shadowneedle" (Unbreakable arrow from module CCC-KUMORI-02-04), which has this special text :
One of twenty unbreakable arrows crafted with Shadowsong [A flavored Oathbow from DDEX03-07 that could be found in Adventurers League play in the past, and is still tradeable today], when this arrow is nocked onto the Oathbow and leveled at an opponent, a gentle hum fills the wielder's mind, steadying their hand and steeling their focus (this feature has no mechanical effect). When [the Shadowneedle is] fired from Shadowsong, the wielder may say the words "Needles, return to your thread" to make this arrow (and any other in its set loosed from the wielder's hand) reappear in the wielder's quiver.
However, ammunition are generally considered as Consumables according to the AL FAQ :
Consumable magic items. Scrolls, potions, soul coins [...] and magical ammunition.
And the Dungeon Master's Guide has a section on such items :
Some items are used up when they are activated. A potion or an elixir must be swallowed, or an oil applied to the body. The writing vanishes from a scroll when it is read. Once used, a consumable item loses its magic.
Does that mean that a Shadowneedle, even when shot from Shadowsong, loses its magical properties and thus won't fly back when the words are spoken ? Or am I (hopefully) missing something, making the "reappearing" property of the Shadowneedle function properly in AL play ?