I can reproduce the issue whenever I want.
Open the game, try to join a server(doesn't matter if quick match or lobby), join button doesn't work and nothing happens.
Close the game, go to My Documents/My Games/KF2 and delete it.
Check the game for missing files through Epic Client, download them, open the game, and you can join and play until you close the game and it happens again.
One weird thing: When deleting KF2 folder, it doesn't auto-refresh. Meaning I have to press F5 for the folder to actually go away. If I try to open after deleting, it will show a error saying it couldn't localize the folder. This 'thing' with the refresh only happens with this folder, could be the issue.
Open the game, try to join a server(doesn't matter if quick match or lobby), join button doesn't work and nothing happens.
Close the game, go to My Documents/My Games/KF2 and delete it.
Check the game for missing files through Epic Client, download them, open the game, and you can join and play until you close the game and it happens again.
One weird thing: When deleting KF2 folder, it doesn't auto-refresh. Meaning I have to press F5 for the folder to actually go away. If I try to open after deleting, it will show a error saying it couldn't localize the folder. This 'thing' with the refresh only happens with this folder, could be the issue.