Using 2 resource packs which both change the colour of foliage causes all foliage (except birch and spruce laves) to turn grey

I have 2 resource packs which both change the colour of foliage, and I put them both on at the same time, and all foliage just turned grey! I am unsure of how to reproduce this bug, but using multiple resource packs which change the colour of foliage should help.