When using a virtual texture sampler for a thin translucent material, and that material occludes other objects that sample virtual textures, the occluded objects don't stream their VT.
For a project that has virtual texture enabled.
Create two nested spheres.
On the inner sphere use a material that samples a virtual texture to output the BaseColor.
On the outer sphere use a material that is set to Thin Translucent and samples a virtual texture to output the TransmittanceColor.
While viewing the spheres, flush the VT cache with r.VT.FlushAndEvictFileCache.
Note that the virtual texture on the inner sphere will low res and blurry.
It's expected that the virtual textures look full res.
Attached project has repro content.
There's no existing public thread on this issue, so head over to Questions & Answers just mention UE-161869 in the post.