1.0.0: Only a few biomes are spawning

[Verdiss]

Version:
1.0.0

What is the bug:
A select few biomes are the only ones spawning in the game. Upon reinstalling the pack, the biomes changed, but the problem remained. The pack is completely unchanged on both installs, and ATG is disabled.

Mod & Version:


Paste.feed-the-beast.com log:


Can it be repeated:
Yes. A new game will yield the same few biomes spawning, and a complete reinstall of the modpack resulted in the same problem, though the biomes changed.

Known Fix:

 

[Verdiss]

Update: I have done a bit more testing and here are the results. Every new game seems to be associated with a certain set of biomes. Here's a list of each new world and the biomes:
World 1 and 2, for some reason they were the same, spawning a swampland, the roofed forest, a couple of foresty biomes, taiga, and extreme hills.
- Re-install of the modpack -
World 3: desert, forest, roofed forest, extreme hills, savannah.
World 4: Woodland, birch forest, extreme hills, mushroom island, swampland, and magical forest.
- Enable ATG -
World 5: Shrubland, jungle, swampland, woodland.

 

[Verdiss]

Update 2: I think I might have tracked down the root of the problem. I re-installed a third time and generated another world (default terrain gen, no ATG.) after what was literally 45 minutes of flying, it looked like I was going to have to write this world off too. I had seen nothing but desert, mesa, savanna, forest, and plains biomes. But then I spotted an extreme hills, next to that a marsh, a roofed forest, and a (snowless) taiga too. I still have yet to find a dedicated snow biome or a jungle, though I spent 30 more minutes flying trying to find those. I think the problem might be a bug (?) with the temperature mechanic. I haven't played 1.7.10 before so I hadn't seen this before but worldgen is supposed to avoid putting cold and hot biomes next to each other. This appears to be happening on a grand scale, where temperature zones are thousands of meters in diameter, essentially creating whole continents of deserts and savannas, as was the case with my initial assessment of this world. Maybe this isn't a bug, but something that is intended to happen, caused by either minecraft or possibly a mod, but it's broken either way. Having to creative mode fly for an hour and change to find a variation in biome is not right.