A barrel will let a redstone signal pass through it, but when the world is reloaded it seems to act as a transparent block (no redstone will pass through). To currently fix the issue, the barrel must be broken and replaced in order for the redstone signal to pass through it again.
Linked issues
Comments 3
This is a duplicate of MCPE-46742.
This is a duplicate of MCPE-46742.
Can confirm in all 1.12 updates, on xbox mobile and windows 10! 😃