Hairline issue

Hi. Theres the right side of the body and the left one, they move, morph, display textures differently. So when you flip something, you need to re-do everything beside vertex paint
I'll write it as a mini tutorial:

1. In S4S main menu, choose Create CAS standalone, click CAS, find the right hair, Shift-click on it to select all swatches, click Next, name it Hair, save somewhere;
   
2. Press Shift-Ctrl-C to open a console, paste studio.exportall. This prompts S4S to create a folder named HairResources in the same location as the package and export all resources in it;
3. Open LOD 0 blend file. In the outliner select the base shape, Shift-click on others to select all 3, switch to Edit mode;
4. In 3d view select everything with A, change the pivot to 3d cursor, Mesh - Mirror - X global;
5. With everything still selected, Mesh - Normals - Flip;
6. Enable X ray, press B, select one vertex in the middle of the geometry that covers the hole in the hairline. If you accidentally select something else in the back, deselect it. Press Ctrl L to select this whole geometry. Press Ctrl I to invert the selection. Mesh - Merge - By distance;
7. In UV Editor select everything with A, choose DiffuseMap in the drop down;
8. Switch pivot to 2d cursor, change Location X to 512;
9. Switch to Face select, press B and select everything in the hairline area, UV - Mirror - X axis;
   
10. Select each s4studio_mesh_, switch from uv_0 to uv_1;
11. Select all 3 again, in UV editor change Location X to 0 again. Select everything, UV - Mirror - X axis;
12. Select the base shape. You should rename existing vertex groups instead of transferring them from something else, otherwise weights will be messed up along the hairline. In the search bar type in R_ . This will show you all bones from the right side that you need to rename. So double-click on one, change R to L, continue until no bones are left in the list;
13. Change R_ to L_. Bones that are named like b__L_Clavicle__ you rename to b__R_Clavicle__. Bones that are named like b__L_Clavicle__.001 you rename to b__L_Clavicle__ . Be careful to not accidentally remove something else, the names matter;
    
14. Select both hat chops, add Data transfer modifier, choose Base shape as Source object, enable Vertex data, then Vertex groups. Choose Nearest face interpolated. Click on Apply button and choose Copy to selected first, then apply. Apply it to another hat chop as well;
15. If working in Blender 2.76 - 2.79, 3.6.1 with all meshgroups selected, switch to Edit mode, select everything, Mesh - Weights - Clean, with Subset set to All groups;
16. Regardless of your version, with all meshgroups selected, switch to Edit mode, select everything, Mesh - Weights - Limit total;
    
17. Save the file. Then add Decimate modifier to all 3 meshgroups, reduce factor, replace LOD1. Reduce some more, replace LOD2 and LOD3;
    
18. Go to Photopea, open Swatch_1_Diffuse_1, rename the layer from Background to Swatch_1_Diffuse_1;
19. File - Open and place, select all other Swatch_x_Diffuse_1 and Shared_Shadow_1, place them. Specular and normal files are of different sizes, so edit them later individually;
20. Select all of them in the list with Shift, RMB-click and choose Rasterize;
    
21. In the top panel go to Windows, enable Actions, open that window, create a new action, press Record;
22. Choose Rectangular select, select the head area from one side to the side, Edit - Transform - Flip horizontally, click somewhere to deselect, stop recording;
23. Select free transform and delete it in the list ( this seems like a bug with Photopea );
24. Select the next swatch in the list, click on Apply button. It should flip automatically.  Do this to all other layers;
25. File - Export layers, disable "only layers blabla" and " trim transparent parts", export;
26. Open Shared_Specular_1, select the head area, flip, File- Export - PNG. Do the same with the specular mask and normal map;
27. Move all of these downloaded files into HairResources, replace all existing ones;
28. Open the package with the hair, open console, studio.importall
    

Did you restart from a new file or used the one you shared?
That one had vertex paint modified, which is what leads to this issue
If you did everything as explained in the mini tutorial, share your blend file please

Are you on mac? Today we discovered that theres something wrong with vertex paint preservation on Aurora specifically. This should not be a problem with Star, though
If you do have Aurora, you'll have to wait until Andrew updates it, though. If you have Star, could you please share this unmodified blend?

As for your files:
Before, i've done this to one meshgroup only and did not account for the fact that vertex groups are renamed for the active object only, not all selected one, so this is partially at fault, my apologies.
However, you have to re-do this whole process because of two other things:
1. When you merge vertices between the geometry that covers the hole and the hairline, the hairline's weights and vertex paint mess up, so this geometry must not be selected when you do this.
If you wont merge vertices, the mesh will look ripped in-game.

- when flipping uv_0, you were in vertex select mode, so some vertices on the hair strands flipped as well. Now the whole uv_0 is messed up.
Unrelated, but when you were flipping uv_1, not all uvs were selected, so some remained unflipped.


I simplified the tutorial to work on LOD0 meshgroups only and create other lods with decimate. Theres a chance that decimate will rip uvs, so I wanted to avoid this. If you do have Aurora, you'll have to wait, though

Hi, andrew . As you said, there may be a vertex paint related problem on windows as well. Take a look at this file