We fixed this problem. Purchased Catalogs will synchronize during the next 24h automatically.
If you want to fix this problem immediately you can follow this tutorial:
Go into settings on your iPad
select the Roomle App (you have to scroll down the left bar a little bit)
click Roomle - and activate "Reload Catalogs"
restart Roomle and you are done
ps: the reload catalog activation will deactivate after catalog is reloaded!