What's happening? :

 The structure block itself works as expected, and everything else works as expected, but when loading a structure that has observers, the observers will pulse, I only noticed this when I was using structure blocks to clone a RAM with copper bulbs (clone in this case means that I used a structure block to create the structure and move it elsewhere), that I am working on, I noticed that all the copper bulbs were on, thought nothing of it and just replaced them, but when I made a binary decoder just earlier today, I realized that the bulbs were being pulsed once somehow, hence how I figured out it was the observers, as one of these bulbs should've been always on in the decoder, but when I loaded the structure, it was off, and the rest on.

This isn't a game-breaking bug, but is definitely annoying considering that having to replace many copper bulbs in a large system being loaded by a structure block could cause frustration.

I will attach before and after photos of the binary decoder being loaded by a structure block in the attachments, the before photo is the one with the right copper bulb on, and the second photo is the one with the three lamps on (this is after 2 ticks), the third photo (after 1 additional tick) where the opposite copper bulbs are on (and the bug does not care about waxed and unwaxed, I have labeled such bulbs), the final photo is after the lamps turn off (+5 game ticks).

How to reproduce

Place an observer facing a lamp, or any type of copper bulb, and then make a structure of it; after that hit save in the structure block, and load it elsewhere, the redstone lamps will pulse, and the copper bulbs will switch polarity.