In the next days there will be a small patch to fix the "Internet Games" Serverlist in TacticalOps 3.5.
Detailed informations will follow with next news and release.

BUT: YOU (the Serveradmins only) should prepare your gameserver-settings.
Please ensure that in the TacticalOps-Server.ini of your Tactical Ops Server the following 3 lines starting with 'ServerActors=' exist : (if not - add these lines)

[Engine.GameEngine]
ServerActors=IpServer.UdpServerUplink MasterServerAddress=master.qtracker.com MasterServerPort=27900
ServerActors=IpServer.UdpServerUplink MasterServerAddress=master.333networks.com MasterServerPort=27900
ServerActors=IpServer.UdpServerUplink MasterServerAddress=utmaster.epicgames.com MasterServerPort=27900

Also ensure that your networkfirewall allows outgoing UDP Traffic to the MasterServerAddress.

Please remove the following line from your TacticalOps-Server.ini - the gamespy-masterserver is history.
[Engine.GameEngine]
ServerActors=IpServer.UdpServerUplink MasterServerAddress=master0.gamespy.com MasterServerPort=27900

These settings are recommended for ALL gameservers running the UT-engine, because we found that there is a major difference in the amount of servers shown in the serverlists of the masterservers.
Using these Settings will give a common Basis for all Players.