Some features from /placefeature create ghost blocks

The Bug

When using the /placefeature command to place features, some of them load server-side but don't show up client-side, creating ghost blocks.

Visual Demonstration (command entered is the one shown above):
https://gyazo.com/55d7ebf9f95660fbccf172ff44fd7d16

Features Affected

• minecraft:forest_rock

• minecraft:pile_pumpkin

Reproduce

• Do /placefeature minecraft:pile_pumpkin ~ ~ ~

Observed Result

The game said it was loaded but nothing appeared.

Expected Result

The blocks would show up, as they were actually loaded.