When blueprinting a train on a diagonal rail, train wagons may not appear in the correct locations if the placed blueprint is near the original (or likely near other rails.)
Example video.
[kovarex] [0.17.9] Blueprinted trains snapping to wrong rail/not appearing when blueprint is near adjacent rails
Re: [kovarex] [0.17.9] Blueprinted trains snapping to wrong rail/not appearing when blueprint is near adjacent rails
Thanks for the report, fixed for 0.17.13