Post the reference of the brick in LDD and we'll look into it. 😃 When parts are available in LDD but not in Mecabricks, the bricks disappear.

But it IS available in mecabricks and LDD. Its actually a subpiece its from piece 76382  
https://brickset.com/parts/design-76382
These are the 2 pieces that disappear

https://www.bricklink.com/v2/catalog/catalogitem.page?P=981982#T=C

But I've seen mecabricks with that piece, I've even used it before, its just when I upload a lxf is when they disappear.

Also piece
https://www.bricklink.com/v2/catalog/catalogitem.page?P=20953pb01&ccName=6124643#T=C&C=1
,
https://www.bricklink.com/v2/catalog/catalogitem.page?P=92944#T=C&C=59

And
https://brickset.com/parts/4552419/wig-w-long-ponytail

All disappear.

I've just placed a brick with id 76382 in LDD and imported it, the brick is fine imported and correctly in Mecabricks. 😃 Are you sure that it was this brick?

I've filled in the data for 20953. It will now import correctly. We do not support decorations yet, so when you use this decoration, only the brick will be imported. You will need to manually replace the brick in the decoration.

92944: I can't find this part on Mecabricks. If you have seen it, let me know! 😃

62696 (wig): This part is imported correctly for me.

62696? sorry my mistake I mean 92257 https://brickset.com/parts/4621315/wig-ponytail-1thats the piece that wouldn't import

Maybe I should try 76382 1 more time. hope it works.

For 92257, this is because it doesn't exist in Mecabricks. Obviously, it only converts pieces that are available in the part library. The others are ignored.

Maybe I should try 76382 1 more time. hope it works.

So 92944 doesn't exist in mecabricks either. But for sure piece 981982 exists I've used them before. They just disappear when I import lxf

okay, I tried it again... it did the same thing again. maybe I'm doing something wrong. please look at these screenshots and tell me what's wrong https://drive.google.com/file/d/1-mGRiXG_RL9435c0CHUsaA55K0MF554n/view?usp=sharing

This is because you used the assembly 16360 - Mini Upper Part 2K.
2K arms have a different part identifier in LDD. I added references 16000 and 16001 in Mecabricks. It is working now.

Thank You! I'll try it.

It works! thanks!