Using the skyexchange pack on curseforge, I found that there are many objects to which the pipes simply won't connect. Other blocks like hoppers or transfer nodes push/pull from those objects just fine. Some examples are the projecte blocks, and Extra Utilities 2 blocks.

and i want to add Immersive Engineering as another example - at least Fermenter wont connect with transporters. at same time, EIO item conduit connect just fine to this machine.

The Harvester from Minefactory Reloaded will also not connect to logistical transporters.

well, i think we need to mention what version (mekanism and/or MC) we talk about. because i talk about version for MC 1.10 and i think LucidCrux too (because Extra Utilities 2) while MadEgg mean MC 1.7 i guess (because Minefactory Reloaded)

Ah, yes, sorry. I am talking about MC 1.7.10 indeed. For me, the MFR Harvester is the only issue I've experienced with transporters not connecting though. They do connect with the MFR Planter, for example.

The exact version is Mekanism(Tools|Generators|)-1.7.10-9.1.0.281.jar, as used in pack BTP-Reborn-Release_1.0.