Mesh looks fine in s4s and in blender but not in game

Hi. Neither weights, nor uv_1 transferred. Either you set up something wrong or the reference was hidden/unselectable
Also, uvs are stretched and the mesh in unnecessary dense

- go back to MD, open this file, select all patterns, change tris to quads. Increase particle distance as well;
- export as thin and weld;
- in s4s clone a bra, export, open, rename the meshgroup to Reference;
- import your garment into the scene;
- select your garment, add Data transfer, choose Reference as source object. Enable Vertex data, choose Nearest face interpolated, enable Vertex groups. Enable Face corner data, choose Nearest face interpolated, enable UVs, choose uv_1. Enable Generate data layers, apply;
- switch to Edit mode, select everything with A, Clean with all groups and Limit total;

- add Data transfer again, Reference as Source object, enable Face corner data, choose Nearest face interpolated, enable Vcol, click on Generate data layers, apply;

- rename UVmap to uv_0;
- select Reference, in Edit mode select everything and remove doubles. Disable Limit selection to visible, holding Ctrl, select all areas of the body covered by clothing, Delete - Faces;
- select Reference, Shift-select the garment, join with Ctrl J;
- in uv Editor select uvs of the garment only, assign the template, press S Y 0.5 to shrink them back to their original size;
- now you can move them, prioritizing their intentional placements ( sleeves where arms are, etc. Everybody puts everything in the bottom right corner and you end up with CAS full of items that cannot be used together );
- Do not scale uvs individually unless the difference in quality is acceptable. Buttons can be bigger, the front pattern should not be bigger than the back. Do not rotate them freely, only by 90 degrees;
- assign cut 0000, import back into the package started from that bra

I have also been having a issue when I export form MD into Blender. My garments don't appear on the avatar it's always on the ground so I end up having to position the clothes on the avatar myself.

Hmmm ok that makes sense thank you

1. See the squares your top is made of? The more of them there is, the worse the garment behaves and the greater impact it has on game performance. Right now the polycount ( number of those squares ) is high enough to crash the game for most people. You were meant to increase particle distance, not lower it.
2. Do not use Remesh. See all those tiny triangles along patterns' borders? They serve no purpose, only increase the polycount;
3. Garments with loose sleeves need to be made with arms down, this shirt will not behave right in cas no matter how you rig it;
4. The reference you chose was too short. It must be of the same length or longer;
5. There was no need in removing uncovered areas from the reference, no need in joining the reference with the garment, this accomplished nothing, no data was transferred this way;
6. uv_1 did not transfer, uv_0 is messed up;