Mali traders lose toll tickets when walking next to a tower even when no toll is collected because its too close to the previous tower.
If you place 5 towers close to your market, a freshly loaded trader will lose all 5 tickets immediately but only collect one toll and all other towers along the way are ignored.
Also, if you have a line of towers slightly too close together, it restarts the distance calculator at each one, even if not collecting a toll. So you might have 8 equal spaced towers across the map but only get 1 toll. This can happen accidentally or when adding towers to protect a resource, king, wonder, etc. Instead, the distance calculator should only restart when a toll is collected.
There might also be other bugs. Mali trade feels much weaker. I used to fast wonder in like 16:40, now it takes 20 min.
EDIT: I found 1 more related bug: towers that are built close to a market receive less toll, and it seems to scale based on how close they are to the market. Building a tower on the market will use up a ticket but generate 0 toll tax, from freshly loaded /created traders… In a 1v1 game, if you space towers far from your markets, and space perfectly, I think you can get a maximum of 3 full tolls–even if the neutral market is in the corner like in Altai.