/testforblock doesn't work with minecraft:double_plant

Using the /testforblock command to find Sunflowers, Lilacs, Rose Bushes, and Peonies does not seem to work. I have tried testing for the top and bottom blocks and it does not identify the block correctly. It does not work regardless of wether or not id: "175" or data name: "minecraft:double_plant" is used. Tested with all four flowers.

Here is the output I got for: "/testforblock 515 53 423 minecraft:double_plant 5" Which should search for a peony at (515,53,423)

[18:21:24] The block at 515,53,423 is tile.air.name (expected: tile.doublePlant.name).