Trident sometimes doesn't activate sculks when striking a block (after thrown), depending on where the player that threw it is standing. 

I can replicate it by making the setup in the attached picture. Standing between the two stem planks on the ground and throwing a trident at the tinted glass in front of the skulk results in one signal strength. Standing between the plank and the tinted glass on the ground (closer)- or the lamp and plank (farther), and throwing a trident at the same spot results in no detection from the sculk.