Currently having issues with the 1.19.3 version of litematica where bringing schematic files to different worlds or servers doesn't work. I've gotten it to copy and paste the hologram of a build on a server but single player wont allow it, the block data for the build will cross over but the actual hologram its self will not. The only thing that appears is a blue or orange hologram box when I try to load the schematic.

Do you have the schematic rendering disabled (M + G) or are you in a render layer mode such as Single Layer?