For some unknown reason, the contents of slices were lost in all documents of some custom types. Before detecting this, we had carried out push of two customtypes (one was affected and the other was not), in this push nothing was eliminated or modified from the customtypes model, only an extra tab was added.
Welcome to the Prismic community,
I will try to investigate this issue with you; one way that can cause this behavior is if you overwrite a certain custom type that is not compatible with your content.
But to be sure, I would need to have your repository name to be able to investigate.
Looking forward to your reply,
Also, it might be that you have changed the API Id (UID) of some pushed custom types, but in any case, you can revert to the old custom types if you haven't republished any documents without getting to the previous state of your content.