We are having the EXACT same issue except that we cannot even open a smaller file or the sample file.  I have gone through ALL of the same steps multiple times and in multiple order trying to resolve this.  The only common denominator is the upgrade from 2021 to 2023 - we had virtually NO issues in multi-user mode in version 2021 or earlier and we have not yet been able to use 2023 in multi-user mode after installing the update 2 weeks ago.  Has anyone found a solution to this problem, which seems to be a 2023 specific issue?