Currently, if you leave a guild during a conflict for whatever reason, the system prevents you from joining another guild until that conflict expires (even if it is completed before then). This is by design and in itself is not a problem. The problem is, if you are not in the guild, you have no way of knowing when that time is.
If you try to accept an invite to another guild, the only information you get is:
INFORMATIONYou cannot join a guild before the expiry time of the conflict initiated by your previous guild while you were a member.
Unless you were diligent in recording the end time of any conflicts before you left, you have to keep trying periodically until it lets you in. Even if you were diligent, if someone initiated a conflict a second before you click "Leave Guild" you have absolutely no way of knowing.
If there was a countdown on the Join a Guild page or time-stamp in the above message as to when you can join the next guild, it would serve to alleviate a lot of frustration when switching guilds.