The slicing engine is going to attempt to print your object with as little superfluous movements as possible. When printing multiple objects, this will attempt to reduce the travel moves as much as possible between the two. This causes different stop and start points on each model to be different affecting the Z seam.
We have not seen this one before. If you can replicate the issue, can you submit the gcode file along with the settings used on our work board for investigation? LulzBot 3D · GitLab
We have seen this one as well, and are looking into a possible re-write of the model positioning algorithm. Unfortunately, for the time being manually placing duplicated objects is required. LulzBot 3D · GitLab
We have not seen this one internally. What OS, printer/tool head, material and profile were you running? We would like to try to duplicate this in house.
It sure has!
If you would like to give the Alpha a try, you can find directions on setting it up here: Cura LulzBot Edition version 3.2.11: Alpha Testing Be sure to clear the cache after installing, as it can prevent some major conflicts!