I've had this issue, I think, since upgrading to the last FAF client. Whenever I join 2v2 matchmaker, if it finds a match, it starts up FA and goes to the 'Connecting' screen, but never finishes loading. Haven't checked 1v1 yet, will add when I do.
Will try a reinstall of faf. If it works I'll update. Any other ideas? Thanks in advance!
You need to make sure you download the maps first
Under 2v2 queue button is maplist make sure these are all installed.
If someone in game doesnt have map installed the game wont start.
Ras Boi's save lives.
Shouldn't it auto-download? It would be very tedious if all have to manually download the map pool each time.
Hmm I think the maps used to auto-download, or at least, I didn't have this issue before. But I see a few maps I don't have yet, so will try this out. Thanks for the suggestion NoOneCares 
They do auto download when you start a match the issue will be if the download takes a while the server will cancel the match because it thinks your machine is not responsive.
Seems that downloading maps has fixed it. Blazing fast fiber here though, so doubt the download was a problem, unless it was a network or server side issue. But if it is, it's very consistent, which would be weird.
@techyon It's mostly like a FAF server side thing or just your general connection to it. I have a hardwired 1gb fiber connection right into my PC and sometimes it still takes me a little to download a map or mod. I've downloaded 2GB+ patches for games on steam faster than I've downloaded some FAF maps before.