Incorrect (fixing) model rotation in UnityBoth Blender and Unity use different global axes or orientation - in Blender "Z" is "Up", in Unity it's "Y". When Blender made models and meshes are imported this difference often means they're flipped on their back (rotated around what is Blenders "X" axis). To fix this;
FIRST (
important!): set the objects "
Rotation" property ("N") value for "
X" to "
-90" and then
reset the mesh using "
Apply" ("
Ctrl+A") - this resets the mesh to essentially lie on its back with an "X" value of "
X: -90" (minus or negative 90 degrees).
SECOND (
optional): rotate the object back to its original 'upright' position and then continue working or export. This will modify the "
X" rotational value to "
90°", i.e. plus or positive 90° (degrees), "
X: 90". Do NOT reset the mesh.
Once the rotational value is set export as normal - when exporting there's no need to set the "
Forward" or "
Up" axis information in "FBX Export" properties as Unity ignores this in favour of deriving rotation that from the FBX file itself, i.e. the actual orientation of the models in the Scene.
IF the mesh is not rotated to its original position after compensating for the above do so to continue editing and working on it ("X" will then become positive 90) - if any changes are made to the mesh or Object make sure to go through the process above again to address rotational issues.