Happens in any group? Not sure how that's possible. Both columns has 0 (zero) as default value and pass zero if they're disabled. I'm able to save any combination in groups: can invite and unlimited invitations enabled, disable, one enabled and other disabled, and vice-verse. No error.
Update your install, btw. You're not using the latest. If it insists, send a PM with an ACP account. I'll take a look today later or tomorrow in the morning.