Steam, PC, Mouse/Keyboard, latest & greatest (947).
I can repeat this over and over. I have video and a save of the Saved directory copied after the end of the day (that I took the video).
[Note: I thought this was a snow-related bug but it happens whether or not it's snowing].
To repeat this:
I had 4 looms set on on either side of two Auto Chests.
loom - chest - loom
loom - chest - loom
I moved all of them elsewhere on the farm with the architect desk.
I then added two looms and another Auto Chest.
The space between the middle chests is visually corrupted, and the newly added looms do not appear to get material, although the graphics show the material going down the moving belt.
loom - chest - loom
loom - [mess] - loom
loom - chest - loom
The next morning it's fine.