I have created an exercise with Ricecooker in a kolibri studio hosted on my own server, it does not show any error when creating or publishing it.
I installed kolibri (not the studio) on another computer to be able to access and use the exercise that I created earlier, I don’t get any error when importing the channel and adding the exercise, but when using it I get the following error:
I also tried the same with studio.learningequality.org and when importing you don’t see problems.
PS. The exercise you create is the same as the one in the documentation.