Details section disappearing

We are seeing multiple instances of the DETAILS section disappearing, in ours and our clients' Zoho CRMs. It seems to be maily where there are some Activities associated with the Record.

It just displays the words "undefined" and "Loading..." where the Details and related lists should appear.

Clearly the link has been lost somehow between the Main record and the associated Details section.

This is a serious bug and needs to be fixed urgently, as it will effectively inhibit proper use in a fundamental way.