I have experience this thing too both in pc and mobile, when i log-in it always take me back to home screen. What i did was, i tried to delete the browser history then after that it worked for me
I don't know if this would solve the problem but here is an idea.
Put a contribution point system in Guilds so when players take an item they will need to save contribution points first.
How does a player earn CP(contribution points)?
*Hunting exp. contribution
*Guild donation
*GvG participation and other guild group things like titan hunting etc.
Also guild items cannot be sent to other players directly, they can only be stored and get in the guild store to prevent hording items (though this would mean expansion of GS space).
Also when a new player join a guild he is given free CP's se he can start with a little ease.
Also the guild loyalty level can increase the CP you earn.
I think this will address the issue of hopping guilds.