Well, what inbound QoS does is dropping packets when the number of arriving packets exceeds the bandwidth limit set by QoS rule.
I suspect that the connection test is trying to transfer the data at a high speed, and when it sees lost packets (caused by QoS kicking off), it complains that "communication features of some games may be restricted". In reality, it may not be a problem during the game - IF allowed bandwidth is enough for voice communications.
However, it's always a good idea to not restrict the inbound bandwidth for the classes you want to have the highest priority.
You can find a lot of discussions on linksysinfo forums about the usefulness of inbound QoS and whether or not it makes sense to utilize it at all - because you can't control how fast packets are arriving to your network from the WAN, the only thing your router can do is to drop packets if they are coming in too fast, effectively slowing the TCP traffic down (but not UDP though).
Personally, I only restrict the inbound bandwidth for the lowest priority class (P2P traffic).