Blender to Unity preview rotation

Hi all,

When I try to import a model to Unity from Blender, the model in Unity's preview appears rotated, when I drag it into the scene panel it is rotated correctly. This only happens though when the model consists of several objects and in Blender I join them by hitting CTRL+J. If I leave the objects seperately and import to Unity the model appears right both in the preview and in the scene/game panel. I tried to import to Unity as a blend file and also I exported from Blender as an fbx, but the result is the same. I also tried to rotate the model in Blender on the X axis by -90 degrees and applied the rotation. As a result the object appeared correctly in the preview and rotated in the scene panel. I need a solution so that a model which consists of several parts appears as one mesh with correct rotation in the preview and in the scene panel.

Thanks in advance for any help.