Conditional fields not appearing

Hi, we have a problem with conditional fields not appearing.
When you select a training course, there should automatically be a field with dates that appears.
I copied to the test form: http://conditional-fields-cf7.bdwm.be/form-tester/?hash=c1cddf3b98d7d9f67d531d8ffed4615d

Until a few days ago it worked very well. Can you help me ?
Thank you so much.