Everything not aligned to the isometric grid

[Vivilama]

So, all of the sudden I noticed that all my vector layers are distorted/skewed and don’t lie on the isometric grid anymore. 
how is this even possible? 
 

I checked the shear option but it’s at 0.0.

[NotMyFault]

Do you have the file saved with history, or still open?
 

1. Save a copy of file with history.
2. check settings of grid. Did change anything without noticing?
3. close the file. Close Designer. Reboot iPad. Sometimes the rendering gets erratic.
4. inspect for any „rotate“ entries in history log.
5. Did you stretch the objects? This changes angles. Check if rectangular angles of objects have the correct angle in grid.
6. did you add artboards, or changed document size?

 

[Vivilama]

Thanks NotMyFault ,
So i did Undo to the point where it said “Undo Transform” which revert it to the correct state. 

I don’t understand what kind of transform I accidentally did there. 
yes I use artboards.