@lbwarped Proxmox apparently uses the Ubuntu kernel (LTS maybe, I don't remember).
So I'd kind of expect the problem to also be reported for Ubuntu systems if it's not due to an interaction between the kernel and something Proxmox specific as well.
Doing a quick search I found a post (Linux Mint post that is currently using a 6.8 kernel like ours) that may suggest that the problem in fact maybe linked to the Veracrypt volume being formatted in exFat. This is in fact the case with my setup - as I want to be able to read the directory from a Windows machine too.
The user on that post, seems to have solved his problem by using an NTFS volume instead.