When this happens, a lot of the time dragging the deco around the board and rotating it several times can help. Don't ask me to explain it cuz I have no idea why but I can say it has definitely worked in the past.
If, after trying the above, you still can't get it to show, we've been informed in the past that uninstalling and reinstalling the app can help with most graphical issues. If you do reinstall the app, don't worry if you see even more blank spots in your bakery after first opening it - it will take a while for all of the graphics to reload to your device.
Finally, if you're still unable to see the deco in your bakery, you'll have to open a
Support Ticket with the team so they can look into it. Good luck and hope this helps!