There may be another bug related to this one:

When polymorphing into a character with a visual set, equipping armor will make that section of the body invisible. Despite this, the character renders correctly in the equipment menu:

[Linked Image]

I did discover a workaround to this, which is done by equipping an item that has the following visuals disabled:
[Linked Image]

This item is equipped by the polymorph status, to the Overhead slot.

Polymorph status:
Code
new entry "TME_SHAPESHIFT"
type "StatusData"
data "StatusType" "POLYMORPHED"
data "ForGameMaster" "No"
data "InitiateCombat" "No"
data "DisplayName" "Shapeshifted"
data "Icon" "unknown"
data "FormatColor" "White"
data "StatsId" ""
data "StackId" "Stack_TME_Shapeshift"
data "PolymorphResult" "faff1221-cf8d-48a8-ad17-16acb1e4e8c1"
data "Toggle" "Yes"
data "RetainSkills" "Shout_TME_Shapeshift"
data "Items" "LeaderLib_ArmorVisualsDisabled"


Armor stat:
Code
new entry "LeaderLib_ArmorVisualsDisabled"
type "Armor"
using "_Overhead"
data "Act part" "1"
data "ItemGroup" "LeaderLib_ArmorVisualsDisabled"


ItemProgressionVisuals:
Code
new itemgroup "LeaderLib_ArmorVisualsDisabled"

add levelgroup 0,0,"All"
add rootgroup "94ef2c7b-099b-4ccb-ac16-d79db4314381",""
add namegroup "EMPTY","",""


Result:
[Linked Image]