Logging this reported issue here, so people know we are already aware of it!
If you are exporting a larger pattern and it takes a while and you decide to continue using the app, if the currently shown design changes, this will be reflected in the part of the patterns that’s being exported at that moment. This leads to weird effects:
I created 15 designs and chose export to jpeg it stopped after 1.
On checking the extracted zip file i got 15 images like this one.
Hi @peterscarfo, thanks for the info!
I can see this is actually a separate issue: it is not because of switching designs while exporting, but something wrong with te JPEG export at larger sizes. I will file a bug report for it 
