When activated from one's inventory, tactical lights consistently prompt the player to attach them to a gun. This behavior is similar to manually activating the "Attach gunmod" action available on gunmods – with a menu that asks the player to choose which gun to attach the gunmod to – but it's prompted around once every 100 moves (roughly each turn, though not every single turn, during testing).

The menu can be manually dismissed, but it reappears on the next tick (the next turn/100 moves).
This behavior has been tested on the latest experimental version (as if the time of this writing), and it does not present itself there. Hopefully, this means it's fixed by the time the next stable release gets issued.
When activated from one's inventory, tactical lights consistently prompt the player to attach them to a gun. This behavior is similar to manually activating the "Attach gunmod" action available on gunmods – with a menu that asks the player to choose which gun to attach the gunmod to – but it's prompted around once every 100 moves (roughly each turn, though not every single turn, during testing).
The menu can be manually dismissed, but it reappears on the next tick (the next turn/100 moves).
This behavior has been tested on the latest experimental version (as if the time of this writing), and it does not present itself there. Hopefully, this means it's fixed by the time the next stable release gets issued.