The lwrp-support-2019.1-with-2.1 SampleLWRPScene works on 2019.1.3, but is broken in 2019.1.8. On 2019.1.8 the plane ends up being in the air, while the outline for the plane is on the floor.
2019.8 is not a version of Unity. Did you mean something else?
Meant to type 2019.1.3 and 2019.1.8. Updated in original comment.
The minimum supported version of Unity is 2018.4, and the samples project should not be openable in 2018.1.x. Sorry, I'm still not sure which version(s) you mean.
I had a typo in my reply, but I updated the original comment, my reply, and the title to all represent the correct versions.
I agree that there seem to be some major issues that just don't work with 2019.1.8 (and .7) - that probably seem to have worked with earlier versions
Can you guys please post which versions that you have tested your samples to work with?
+1. The last worked version is 2019.1.4f
I tried describe a little more about issue on the forum.
Is this limited to LWRP-based applications?
I checked only LWRP + AR Foundation.
I have seen this issue on 2019.3.0a8, 2019.3.0a5, and 2019.1.10f1.
2019.1.2f1 worked correctly.
When using LWRP with AR Foundation, it looks like all objects render at the AR Session Origin. The Line Renderer shows the outlines of the planes in the correct location, but the Mesh Renderer renders every plane centered at the origin. I placed multiple objects in the sample scene at different locations parented on the session origin, AR camera, and the world. All of them centered themselves in the same origin when the AR app started. When I remove LWRP, everything renders in the correct locations with AR Foundation alone.

Bumping this thread, seems like the same thing I posted in #212.
@xendav did you find anything more about this? I've even found that planes are being attached to the spawned gameObject. You can typically only see it if they receive a shadow.
@BikutaAnkuta Working on 2019.1.4f (this is the last stable for AR, I think) and can't update Unity version, this is sad (
@BikutaAnkuta I haven't found a solution to get it to work on later releases. They may not be attaching to the spawned gameObject. From what I have experienced, the spawned gameObject and any other object just end up at the same position. I made an object made out of multiple pieces and it showed up in the same place as the ARPlanes with all of its parts centered. The images below are the same scene. I displayed the transform of each object at the top of the screen. When I changed to LWRP, the ARPlanes and all three objects center themselves at a single location. The materials of the three objects render with the parent's material. If I moved closer, the wireframe cube would disappear and the color would change to the color of the next child. Also, the script would no longer display the position of the three objects. @Goncharuk-Nikita I agree. I'm stuck on 2019.1.2f1 to get things to display correctly with LWRP.

@Goncharuk-Nikita @xendav I can confirm that 2019.1.4f1 works like a charm for LWRP, when started from the lwrp-support-2019.1-with-2.1 sample.
@tdmowrer Can we get this branch to ask for 2019.1.4f1 instead of 1.5? It's bound to be a bit misleading.
Please use URP instead of LWRP:
https://docs.unity3d.com/Packages/[email protected]/manual/ar-camera-background-with-scriptable-render-pipeline.html
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I had a typo in my reply, but I updated the original comment, my reply, and the title to all represent the correct versions.