before I try and get access to a Windows11 machine to test this: where are you saving your project? Is it on a drive which is local to the CcpNmr Analysis installation? (That is what we always recommend, as the program writes files very frequently and a drop in the connection could cause issues.)
Is the Autobackup function on (check in File / Preferences)? Are these being written into the project.ccpn/backups folder?
I’m incidentally also wondering how you determine that “the files aren’t written”. Please note that we have changed the way in which we do our saving of projects.
The main part of your project is basically stored in the project.ccpn/ccpnv3 folder. This contains various directories and files with information about your project. When you save your project it is this ccpnv3 folder which is saved and a copy of what it had been before (the last time you saved) is put into the project.ccpn./backups folder. So the easiest way to determine if the save was done, is to check whether the previous version has been saved in the backups folder.