Factorio Forums

When entering editor mode I can no longer place two pieces of cliff next to each other without forcing it with [shift] + [click]. This worked in 17.34. There's no water or objects in the way; I can place the cliff normally if no other cliff is touching it. It's also a problem with all rotations.

Thanks for the report however I can't reproduce what you describe. When I test they don't collide in that setup. Can you post a save file showing the issue?

Here's the save-file. I re-tested it since I noticed I had mods enabled. Without mods, it does indeed work like expected. With mods, it doesn't.
Hive_mind 0.3.1
Redmew_Server_link 1.0.1
Unit_Control 0.1.21

The "Hive Mind" mod is making cliffs collide with themselves by changing their collision mask. Cliffs are not supposed to collide with themselves else you have the problem you're having. You'll need to report it to that mod author or just stop using that mod.