I try with the XPRV but it's the same. empty wallet with balance 0.
That's what I'm not understanding.
You said here that the address is empty when you look for it in a block explorer:
Yes I checked in the Blockchain and it's empty. I opened the file in the text editor but I did not find anything seed or xprv.
So it's understandable that it is also empty when you import it. Open the wallet that shows the 33k BTC balance, then go to View -> Show Addresses -> click on the "Addresses" tab, find the address that has the 33k BTC (or at least most of it) and copy it. Then look for it in a block explorer. If it really is empty, then the 33k BTC is most likely a visual bug or something similar. The block explorers are pretty much always right.