party members not getting put into game when host searches and finds game

When matchmaking finds a new game after the squad leader searches, I get stuck in the lobby or end-of-game screen whilst my squamates are loaded into the game normally. Occasionally I can join them manually from the social page, but usually I have to restart the game.

This is happening more often than not now and I've checked my network settings, as well as cleared the reserved space for the game on the Xbox, but that reserved space is filled again upon loading the game up.