x10 Open Unity(I am using a 2019 version and the lastest 4.0 Spine-Unity runtimes) Go to Assets-Spine Examples-Spine Skeletons-spineboyunity under the Atlas Assets panel, change size from 1 to 2 change Element 0 to something else Step 3 or 4 won't work, but it did in some of the preview versions.
Misaki I'm sorry to hear you're having trouble. Our resident Unity expert, Harri, is currently on vacation. He'll handle it once he's back.
Harald Sorry for the late reply and the troubles! We have just added a commit on the 4.0 branch which fixes the Atlas Assets array immediately resetting in the SkeletionDataAsset Inspector. A new 4.0 spine-unity package is available on the download page: spine-unity Download: Older Versions Related forum thread with the same question for later reference: Atlas Assets parameter in SkeletonData asset