No, they are not the only ones with a lot of problems. Other suffered too. For example Koči with TRT 208 hasn't finished a single WRC2 event this year I think. Princen in Belgium retired or fought with many problems in nearly every rally as well. If You go through WRC2 results You can very rarely find a 208 which finished some event no matter how many of them started. It's more like Racing Lions are the exception from the rule.