Changing channel assignments for one member group disables them for other member groups

Question

Every time I try to create a new member group (or edit any member group that isn't Super Admin) and assign channels and module access to this new group it disables all channel assignments module access in other member groups. If I then go back to the original member group to fix the disabled channel assignments and module access, the new one gets disabled.

It should be noted that I have two add-ons that may be part of the problem. These two add-ons are Structure and Zoo Visitor.

Any idea why this might be happening??

Answer 1

I think, you are using ExpressionEngine 2.5.3. You should see here https://support.ellislab.com/bugs/detail/18234 for the solution.