All Mechanical Pipes won't connect to Thermal Expansion Tesseracts, while Logistical Transporters and Universal Cables will. Other Mods' fluid pipes will connect to Tesseracts, such as MineFactory Reloaded's plastic pipe. Other Thermal Expansion fluid blocks, such as Portable Tanks, do work with Mechanical Pipes.
Installed Mods: Mekanism (Duh), Thermal Expansion (Duh), MineFactory Reloaded (Duh) (And everything those mods require and / or download automatically (Duh))

I'll see if I can track it down. Would be easier if I had their source but I don't so I'll just see what I can do.

I was mistaken. They don't actually contain a tank, so our tank-detection algorithm obviously ignores them. I'll see if I can fix that.

It's either us not responding to a block update and them not sending a tile update, or them not responding to a tile update and us not sending a block update, or maybe someone's just not sending updates every time they should be...