When uploading documents with the correctly oriented pages into FlexiLayout Studio some of them are incorrectly rotated after upload.
Sometimes FlexiLayout Studio may try to correct the page orientation based on the lines available in the documents. FlexiLayout Studio treats them as separators and rotates the page to make these lines horizontal.
As a solution, it's suggested to remove the "Use separators to correct skew" option from Image Preprocessing Settings.
It's possible to do this when uploading images, just click the Batch tab -> Add Images... OR right-click on the images list and choose "Add Images..." from the drop-down menu to get there.:
Check the documentation for detailed instructions.