I have found a bug relating to the recruiting process, which you can initiate by talking to your constable and having him send out a recruiter to recruit soldiers for you. I will explain in more detail below, but here is a screenshot of the error with the relevant text boxed in green.
To be brief, that error repeats itself every couple of days (2-3 game days) and also makes the "money" sound that occurs when you receive loot. You receive your recruits from the recruiter, but that error message occurs once they are delivered to you. Read on for more details:
I started the game as independent and eventually took over Patak Castle. I hired a Constable shortly afterwards and the first thing I did was have him send out a recruiter to Europe to bring back 30 recruits (Peasant Levies). He did so and when I went back out to the world map, I saw the 1 recruiter heading off towards HRE. I went about my business for about 2 days...i forget the exact time it took, but recruiting typically takes 2-3 days. After that period of time, I got the message on the world map that you see in the screenshot above (too many teams for ai, Your messenger has lost it's way and gave up your mission!).
I was pretty far from my castle at the time and just noted it in my head to report. About 4 days after the error, I arrived back at my castle and decided to send out another recruiter. I sent another recruiter to gather 20 recruits from Europe. Checked the world map and off he went, however I noticed that I had 30 Peasant Levies at my castle. Went in to check the garrison and yes, there were 30 Peasant Levies from the first recruiter.
At this point I went back out to run some tournaments. About 3 days later, I get the same error and this time I am close to the castle. I go check and I now have 50 Peasant Levies, which means the second recruiter did complete his task even though this log message says he did not.
I did not send out any other recruiters after this, but the error message continues to occur every 2-3 days and makes the "money" sound as well. As far as I can tell, I do not get any money deducted when this occurs. I am now 40 in-game days past the point where the error first occurred (day 82) and the error message still appears on schedule, every couple days.