Lava glitch in creative

Put the summary of the bug you're having here

What I expected to happen was...:
to get the block beneath the lava when middle-clicking it

What actually happened was...:
I got "Block 10" - a lava source block that spreads (see attachment)

Steps to Reproduce:
1. Place a lava bucket
2. middle click it
3. sometimes it will glitch and give you the lava (Keep trying)