Actually there is already placeholder for this issue in form of bForceTaggedSerialize, where it's suggested that FLinearColor can't be natively serialized for EndWar (even though ItemType imply otherwise) - currently it's not used anywhere. Indeed, if FLinearColor is excluded from native serialization there and in CTypeInfo::SerializeUnrealProps, it's parsed correctly.
Though there is another issue, which presumably came after 64-bit builds appeared. In USkeletalMesh3::ConvertMesh TexCoords are defined as NumTexCoords = max(SrcLod.NumUVSets, SrcLod.GPUSkin.NumUVSets), but GPUSkin is serialized only for ArVer > 333 games and above - for cases like this (ArVer < 300) value SrcLod.GPUSkin.NumUVSets would be undefined. As a result, for 32-bit builds macros "max" is producing correct output due to limitations, but for 64-bit builds it will return undefined value and umodel bump into the next assertion (NumTexCoords > MAX_MESH_UV_SETS).
Probably
that topic may be also related to similar issue with undefined value.
@sp111kg: You can use specific build from
this topic with the same override option for now, I made some fixes based on explanations above. Though you need to disable animations, they are not supported for this game.