You might come across an issue related to saving “Profile Privileges” for each module. It’s a known issue, however it’s not a vTiger bug – it’s a server limitation. If you are a server admin and have access to php.ini, you should check the value of “max_input_vars” and increase it to 1500-2000. By default it’s set to 1000 which is not enough to save vTiger Profile Permissions. If you are not the server admin or are you using shared hosting, you should contact your vTiger hosting provider and ask them to do the same.
Hope that helps!