savannaBiome = forBiomes(35)
savannaBiome.set("foliageColor", 13413215)
savannaBiome.set("grassColor", 13413215)

The above code does not change the savanna biomes grass/foliage color, similar ineffectiveness has been found with attempts to change the color of some other BOP biomes, such as Xeric Shrubland. I suspect this is entirely to do with BOP, since BOP does modify the savanna biome.

https://github.com/Glitchfiend/BiomesOPlenty/blob/BOP-1.10.2-5.0.x/src/main/java/biomesoplenty/common/biome/vanilla/BiomeExtSavanna.java

I'll look into this as soon as I have some free time from classes.

As a side note, the BoP compatibility classes never seem to get loaded. Looking at the code, the text that is supposed to be written in the logs when BoP integration is loaded never gets added to the logs. Log also says that it fails to find meaning in any of the BoP commands.

Turns out the color overrides not working was a bug. You're right that BOP overrides it, but I have ASM code that is supposed to fix that (that wasn't working).

Give the latest a build a try and let me know.

http://jenkins.superckl.me/job/BiomeTweaker%201.11/246/

Weird things are happening. Thought it had fixed it, but the only BoP biome that seems to be working with an override is the outback biome. I'll edit this with a further list as I move around.

Closing this since it's on 1.10.2. Please verify that this is still an issue on 1.11.2 and I'll reopen it.