The four reddish pixels on the output side of the observer block don't light up when it detects a block update Continue reading to understand what the problem with that is.
* Firstly, these four dots are supposed to represent the redstone dust that is used in the crafting recipe so supposedly when it detects a BU they should get lit up as well (they are the link between the redstone component and the dust itself). It looks sort of weird that the dust gets powered but the source itself doesn't.
* Secondly, there is no real way of finding out if the observer block has successfully detected anything without placing redsone dust or redstone lamp etc. The player should be able to do so using only the block itself as far as I'm concerned.
* Finally, all the other redstone components that "transfer" redstone power (repeaters, comparators etc.) light up while that is happening, indicating that RP is going through them whereas the observer just stays the same.
TL;DR There is something with the observer texture that kinda doesn't make sense to me and I want to hear other people's opinion.