This is the second time this has happened to us.

Inside of our creator app, we were editing one of the permission groups.

In the final column 'More' where you specify view all / modify all / etc for each form, we changed a single module to allow a user to 'Modify All'.

Upon saving, instead of updating the individual module, Zoho completely wiped the 'More' permissions from every single module in the permission group (In this case 50+). This necessitated us going back through each and every module and re-setting the permissions.

This is the second time this has happend to us, so it is definitely not a fluke. This seems to be a very severe bug that should be looked into ASAP.