[CLIENT] Accept Match Popup Fail (both BETA and LEGACY)

This is happening in both beta and legacy clients. I don't know if they are the same bug, or a coincidence:

In the BETA client, when I'm queued the AFK check dialog pops up for me to accept a match, it accepts my click, closing the button, but then continues counting down, then eventually tells me I didn't accept, and dumps me. This was happening perhaps 30% of the time.

In the LEGACY client, it is failing to show me a popup AT ALL, or to make the warning sound. After a plausible wait in queue, I am suddenly dumped back at the pre-search screen with a complaint that I did not accept. But, to reiterate, I was never shown the popup. So far, this is happening 100% of the time.

In fact, I just had to switch back to Legacy because of the long delay when entering champ select (which once again made me involuntarily skip queue), and thus far I have NEVER gotten all the way to champ select with the Legacy client. The damned server has now informed me that I'm being punished for not accepting matches, though of course I never was given the chance to do so.

[Edit: Just got through with the legacy client, for the first time. Then someone failed to pick a ban (which should not kick us, I hate that), so I'm back searching again]

Step By Step (though it seems unnecessary for this one):

BETA

1. Launch the Beta client.
2. Click the Play button.
3. Choose (in my case) Summoner's Rift:Draft Pick
4. Click Confirm
5. Choose Jungle:Top (at least that's the only thing I've been trying to play since this started)
6. Find Match
7. Popup occurs normally, click Accept
8. If the bug occurs, the Accept button goes away, but the progress arc continues to advance.
9. After an abnormally long wait, dumps you back pre-queue, claiming you didn't accept.

LEGACY

1. Launch Legacy client.
2. Click Play button
3. Choose Classic:Summoner's Rift:Normal Draft (dunno if it's happening elsewhere)
4. Click Launch
5. Choose Jungle:Top (at least that's the only thing I've been trying to play since this started)
6. Queue Up
7. Wait the normal amount of time
8. Suddenly get dumped back to the pre-queue screen with the complaint that you didn't accept the imaginary popup

I have been running PingPlotter, albeit pointed at Google instead of your server, and have not noticed any network interruption, not even a particularly bad ping, at the point where either of these variations occur.

I'll point it at your server and see if that's different, but at the very least I'm confident that the problem is not my own general network connection.