After processing, there is no Orthomosaic geotiff file in Mosaic folder

Can anyone give me some idea why there is no Orthomosiac geotiff file in Mosaic folder after finishing processing ? Does it cause from the quality of images which i shot or what ? Right now i am using Pix4D pro which has full options to make Orthomosaic geotiff file but as i have mentioned above, there is no orthomosaic geotiff file after processing. before it could output orthmosaic geotiff file after finishing processing but just my last project, it does not output orthomosaic geotiff file.  

How many images do you have ? I did a full 6000+ images and it did not create a full ortho but the tiles yes. (Maybe the ortho would be to large)

Press merge tiles in the processing options and then you will have a full OM