UE5 Not working well!

Hello,
I’ve been making ny project on UE4.26 but I just convert it to UE5.
Since them, everyting become a big mess. Lag, edittor bugs, lumen mess, etc!

My big problem now is with World Partition. I have an Open world landscape made in previous version and I use virtual texturing in it . After converting it to UE5 World parttition, my landscape is not rendering. The landscape is still existing in the outliner but not showing.

If you have any idea please let me know.


Original Landscape in UE4.26

UE5 version.