Altium Designer - Net has only one pin | Pin out of grid | Floating Label | Diferential Pair
For the first errors you appear to have the pins flipped so the active end is not out. Therefore they are not connected even though they look (almost) like they are.
Using a metric grid for the schematic sounds like a way to have a bad day. You appear top have a display grid that's not aligned with your snap grid, for whatever reason.