I realised when I enable tagging module for a taxonomy vocabulary of a content type, all fieldsets on the content submitting form are collapsed and cannot be opened at all. They seem to be inactive.
Also Wysiwyg gets unloaded and not shown around the body text field.
If I disable tagging for the vocabulary, all are up and ok again.

Most strange that my test and live sites have the same modules enabled with same settings. Everything is ok for test site (tagging, fieldsets, wysiwyg) work together well. However on my live site they produce the above error.

Please advise.