Barriers have a way of showing themselves when they are placed, but it seems that the Structure Void doesn't show when holding a Structure Void item in your inventory. This makes it almost impossible to find one after placing.
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Comments 6
Not sure if it is a bug, but a possibility to see the structure void blocks just like the barrier blocks would be a nice feature.
For feature suggestions, go to the minecraftsuggestions subreddit.
Umm, did this get moved to the API section, or did I just mess up the report.