Summary:
Trident is invisible in the players hand in first and third person, unless in first person the player is within range of a block or entity. Or sometimes randomly starts flickering or disappears.

Possible example steps to reproduce, doesn't trigger every time:
1. Create a flat world creative.
2. Equip a trident in first person in creative or survival.
3. Notice the trident is not visible, unless within range of a block or entity (hit range ~<5 blocks).
4. Switch to 3rd person and notice the trident is not visible at all in both front and back view.

Video Attached:
MCPE-31673.mp4
MCPE-31673 (2).mp4

Notes:

Original report:

When holding the trident in game, it doesn't show it. But sometimes it like shows it but not being held correctly. But for me its invisible

Edit:

The bug was fixed on version 1.2.14.2, but still exists on the non beta version (1.2.13.60 and 1.2.16)