Having the same issue. I send an in-game invite to a clanmate, it pops up as a PSN notification, and here's the kicker: If they accept the PSN invite, their game crashes, sometimes to the point of needing a restart to bring the system back into functionality. Not consistent, only sometimes happens, but it's bad enough to mention here.
Doesn't matter if this is someone on the same connection, down the street or across the country. I can't trade with anyone because whether I invite them to my dojo or they invite me to theirs, I'm placed in a separate instance and can't see or trade with them. This has been going on for 6 months but has finally reached a point where the trade system is broken beyond use even after remedial measures. I've been resetting my system, restarting my modem and router, and while this isn't an issue on other games on my PS4 or PC or on my wife's Xbox, it's only happening on Warframe in partic