Recieve “overflow encountered in expm1” when optimize the model

[Fuji-Hitomi]

When I tried to optimize my model ,"overflow encountered in expm1” come out and all predicted output become a constant (like .Sometimes it will disappear when I change the training output with the same input ,and the predicted output won't be constant if there is no such warning.

(PS: As a rookie in machine learning ,it's really confusing that GP performed very very well in modeling this data,but DeepGP didn't get such a good result. I really appreciate your reply.Thank you!)