Affected Platforms:
Windows 10: Yes
Xbox One: Yes
iOS: Yes
Mobs of all types are able to spawn on redstone components. Redstone being spawn proof was specifically added to java around 1.9, A lot of people use redstone dust to mob proof builds. it's a simple way of preventing accidents while not torch/slab spamming everything.
Please note that mobs will spawn on top of ALL redstone components.
Dust
Repeaters
Comparators
RS Torches
RS Lamps
Observers
Droppers
Hoppers
Dispensers
Rails
Pistons of both types.
Related issues
is duplicated by
relates to
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As a redstoner myself I can also confirm this has happened to me on some rare occasions on my redstone world. I’m on 1.2.16 on iPad Pro.

I should note, this also happens on windows 10. It would be nice if we could select multiple affected platforms on the bug report🙂
Included the affected platforms in the ticket description.

Ahhhh, well, i guess that's one way of doing it xD Thanks <3

This bug is not fixed as of the latest bedrock update, contrary to the changelog.
Which blocks are you getting mobs spawning on specifically?
Using 1.5.1.2, I tested a flat world with a 180x180 walled off area, and I placed the following blocks within that area.
In Java (1.13) and Bedrock (1.5.2 and 1.6) mobs did not spawn on:
Redstone Dust
Redstone Torch
Comparator
Repeater
Rails
Hopper
Piston
Time was set to night, difficulty to Hard, and mob spawning was enabled. No mobs were seen to spawn on the components.
Please bear in mind that mob spawning is not disabled on all redstone components on the Java edition either. For example, mobs will continue to spawn on:
Dispenser/Dropper
RS Lamp
Observer
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thanks for being active on this issue! It appears I may have been given some wrong reports about things spawning on redstone. I had multiple people tell me that it was not fixed. So I reopened the bug report.
I am currently away from my pc, but when I return I will also conduct some tests to confirm that things do not spawn on RS components🙂
Ok thanks. If there is broken behaviour I'm happy to reopen the bug for a fix.