Camera.RenderWithShader does not render to texture with OGLES 3, but does with Vulkan?

Some time ago I published a small open-source demo of my idea how to easily render a "Lens flares" effect in 2d games [https://github.com/dotsquid/LensFlares] (how it works [http://dotsquid.com/2019/06/26/simple-gpu-occlusion-for-lens-flares/])

It works fine on Windows, WebGL and my Xiaomi Mi4c with Android 7.1.
But it appeared that it does not work on Samsung S10+ and iPhone 8.
By "does not work" I mean that the render texture used under the hood keeps holding zero values in any case.

I tried to use different formats for the render texture, enable and disable depth and stencil buffers (which are not required, but anyway), tried various manipulations with camera with no luck. And then I tried to use Vulkan and voila - it started to work on Samsung S10+.
But obviously it's not a solution. I want it to work under OpenGL ES on any device as it does on my Xiaomi Mi4c. (I'm using Unity 2018.4.10 LTS)
Any ideas?

{ Not working }


{ Working }​

 

@florianpenzkofer, @richardkettlewell, any one? Push me in the right direction please.

 

Done https://fogbugz.unity3d.com/default.asp?1193036_27o4t4jhlg5r6arl

 

Any news?

 

It's being processed for more than 1 month, which did not happen for any of my previous bug reports. Is it ok?
We have a release date in 2 months and I'd wish to know whether I can expect any information on this problem.

 

Ah, thanks a lot! I was sure that I tried this format and it appears that I didn't. It indeed makes things work on the problem devices.

 

Is there an API in Unity to get information about whether the driver / hardware supports generation of mipmaps for the given format?
I tried SystemInfo.SupportsBlendingOnRenderTextureFormat but it seems it does not work for my case.

 

Thanks!