got the have same issue ... no texture and empty maps
I have 32go ram rtx 4070 ti
Assuming your hardware clearly isn't the problem here;
The map was changed to a new in-progress map, that is much smaller and more streamlined which is making much better progress than the previous map which was far too large.
You may be noticing the temporary placement props and textures, which are there just as a guide to the devs to know where to put things.
Example:
Dev is making the map and decides "I want a little nature area here with a small pond, trees, bushes, flowers, maybe some frogs jumping around. But I can't do that right now, let me place some default untextured prop trees here as a sticky note to myself and the other devs, to build that area here later."
Not talking about the base map?
If you are experiencing texture loss in default sandbox while building your own map or viewing someone else's. Then there is indeed some sort of issue going on in your case.