Hello!

Sometimes loaders don't snap properly to belts or to one another. This is especially evidential when loader is a part of blueprint - belts don't look turning out of loader, just passing by. Aside from visual bug, this also causes loaders to not input/output stuff until replaced by hand.

Thanks.

Do you have a save where this happens reliably?

I have one but it also includes few other mods. I'll try to reproduce it on clean world.

Unfortunately I don't have time to make proper reproduction ATM. Will try to make it as soon as possible. In case it may help, I'm using "nanobots" mod which may be causing these troubles - I mostly observed glitches after ghosts (not BPs) were placed by nanobots.

Silly me. Here are STRs:

1. Have either construction bots or nanobots. Checked with both of them.
2. Pick loader, rotate it to south, place ghost.
3. Pick corresponding belt, rotate it east, place its ghost adjacent to loader so they should connect. No need to either place it before loader is placed by bots or wait for it.
   Expected: blt and loader get connected
   Actual: You need to replace loader to make it connect.

The issue with blueprints happens when you make loader+belt junction as ghosts only and then make BP out of ghosts. More interestingly, if you materialize setup and then make BP out of it, belts look not connected but actually get connected when BP is placed by bots.
I think this is because connection code doesn't run when ghosts are placed, and neither bots make that connector code run.

I can’t reproduce this, testing with both regular construction bots and Nanobots. I may be misunderstanding the layout you have in mind. Can you post screenshots or a save?

Sure. Screenshot with a few comments:
https://drive.google.com/open?id=1PmljX0Re8O9pAaW6rKt4bSz8pVnpdsKG
World save, just in case. Only Miniloader mod:
https://drive.google.com/open?id=1S6hK37hypOuanpsqwkHzNBrTPeiTo1tK

The main idea is to place loader setup you want as ghosts and then allow bots to fill it.

Oh, I see. So the blueprint ghosts initially placed are incorrect: the north-south loader is backwards, with the belt side of the ghost facing the chest.

By design, snapping only happens when building by hand. Miniloaders trusts blueprints, because players may want to do something with miniloaders that I couldn’t think of ahead of time. I could perform snapping when placing belt and Miniloader ghosts though. I wonder if that would be confusing.

I'd expect behavior similar to underground belts - miniloader is rotated manually (only 4 states, not 8) and snaps to near belts which match its direction, like splitters or underbelts. As of ghosts, please note that normal belt ghosts snap just fine. So it's a bit counter-intuitive for loaders to work differently.

The problem is, this would be the analogous setup with underground belts: the belt side of the underground/loader isn't facing another belt, it's facing the chest:

Loaders, like underground belts, actually have 8 rotation states: NSEW, and input/output. I'm not sure what you mean by "normal belt ghosts snap just fine."

Even when the belt-side/hood-side setup is correct, underground belts do not snap in the way you seem to expect:

If you want bots to build blueprints such that the belts connect properly, the entities in the blueprint all need to be oriented correctly.