2 Player won't work

Attempted launching forge with my kid last night. Game simply will not launch it. Custom games work fine. Try to launch forge press play, the countdown goes all the way and then the button flashes orange for a second before reverting to the play button. Tried for about 15 minutes and gave up. Attempted reboots, checking my kids xbox account settings, checking both pcs settings, etc. Very frustrating That and lan loves to crash during custom games. Custom server keeps chugging along but the main client likes to just crap out randomly.