The bug
Observers do not activate when the following changes happen:
A campfire becomes a signal fire (hay block placed below)
Adding an eye of ender to a portal frame
Fire catching on another face of a block
Vines spreading to another face of a block
Fences/panes/walls/iron bars changing connections
Stairs changing shape
Grass becoming snowy (snow placed on top)
Adding/removing a music disc from a jukebox
Adding/removing a book from a lectern
Leaves distance changing (log placed nearby)
Locking/unlocking a repeater
Tripwire changing shape/connections
Snow layers generating from snowfall
Note block changing instrument (block below changed)
Powering/unpowering a note block
Powering/unpowering a door/trapdoor that's already open
Powering/unpowering a mob head
Related issues
Powering/unpowering a hopper: MCPE-40843
Pumpkin/melon stems moving: MCPE-36783
Nether wart growing: MCPE-41074
Note blocks changing note: MCPE-53919
Entering/exiting a bed: MCPE-46345
Rail changing direction: MCPE-30544
Respawn anchor charged: MCPE-75742
Target block getting hit: MCPE-84391
Kelp age changing: MCPE-179683
Various fixed issues: MCPE-14710
Linked issues
is duplicated by 8
MCPE-67354
Observers Don't Detect When The Fence Has Been Connected To A Block
Resolved
MCPE-86359
Observers don't detect "Some" block updates
Resolved
MCPE-100038
When vines are placed on the observer, the observer recognises the vines and updates the piston but when the vines spread from top to bottom through natural growth then the observer isn't recognising and is not updating the piston
Resolved
MCPE-112939
Jukebox doesn't give a block update when playing a disc
Resolved
MCPE-118969
Observers not registering certain block changes
Resolved
relates to 11
MCPE-225461
Observers do not detect shelf contents changing
Open
MCPE-75742
Observer doesn't detect Respawn Anchor charges
Reopened
MCPE-53919
Observers don't detect changes to Note Blocks
Open
MCPE-84391
Observers don't detect target block updates
Open
MCPE-130935
Observers don't detect nether portals turning off
Open
Attachments
Comments 27
None of the "block updates" stated are block updates. The problem does not come from the observer. You can test it using other BUDs, they won't detect them either, meaning they aren't block updates.
This has to be the most annoying bug for most redstone players. Redstone in general needs an overhaul in bedrock edition to let people play seriously, post main game.
tryashtar
(Tested before reported - from 'Technical Bugs List' https://docs.google.com/document/d/1nziKYzCr4pBdCRj2gIMlfr9MVdWHd6HyafdiBHx9F0c/edit)
This issue happens in 1.15.0.53 also.