Riptide doesn't work in rain within a frozen ocean biome

In certain spots in frozen oceans, namely the gaps between icebergs where the water isn't frozen, the riptide enchantment does not activate when it is raining

Expected behavior:
Usually, a player can use riptide while not touching water so long as it is raining, except in snowy biomes or biomes that don't get downfall. When I went to use riptide over a small, unfrozen patch of a frozen ocean, where the snow particles were replaced with rain, I expected to be able to get the riptide boost without issue.

Actual behavior:
However, the trident did not pull back, as if I was still in the snow rather than the rain

Steps to Reproduce:
1. Obtain a trident with Riptide I or greater 
2. Find a frozen ocean biome
3. Look for liquid water within that frozen ocean biome (use the f3 menu to double-check)
4. Wait for it to rain or make it rain using commands. If done correctly, the icy area should have snowflakes falling on it, but the area with liquid water has rain.
5. Attempt to use your riptide trident while in the rain in the frozen ocean, while not touching the water (For example, place a block over the water)