Lightmap meshes limitation

Hello there !

I’m currently doing some interior archviz scene.
Some of my meshes have a 128 lightmap resolution, some 256 … and so on.
I wanted to try a big lightmap for my floor but when i go above 1024,(2048/4096) i have shadows problems all over the level, after the build. (kind of texture streaming issues, but for the shadows)
I there a limitation in the .ini file for the lightmap size or any tricks i didnt get ?

Thanks for your time.
Greetings.