Closely relates to MC-136405.

The bug

Unlike most blocks, when right clicking on a replaceable block such as a vine, if the player is holding a lily pad or frogspawn, that block will not be placed even if it would have been placed in a valid position.

How to reproduce

1. Create a setup with vines against a wall above water
2. Right click on the vines, intending to replace them with a held lily pad
3. Attempt to place the lily pad atop the water directly instead

Expected results

When targeting the vines, the lily pad would be placed.

Actual results

It is not. The lily pad is placed just fine, replacing the vine, if the water is targeted instead.