SMB Shares managed by Nextcloud are not good for the Memories app because it needs to have access to the complete file to analyze it. But there is an efficent way to use it!
Disclaimer: I am a noob doing complex stuff in Proxmox here.Do this at your own risk. I give no warranty. DO A BACKUP FIRST! 😬
While trying to run a docker-compose with a Frigate container inside an LXC container (in Proxmox) I had this problem and finally found the solution.