Sorry I should have read your OP properly... You did already say it was v18.0! Next I was going to suggest that perhaps it got some minor corruption, but you've also ruled that out.
Different to you, I installed the v18.0 LXC template on Proxmox. Although It should not make any fundamental difference - as we create the LXC templates from the ISO. So other than a few specific tweaks required for LXC, they should be essentially the same. FYI I downloaded the LXC template via the "Proxmox Templates" in the web UI. If there were issues, I would expect them to be more likely under LXC, not the other way around.
As you're running the latest Proxmox, that is another difference - I'm still running the older v7.x. But again, I would not expect that to cause any fundamental difference in this case. While newer versions of packages on the host may cause some different behavior in guests, if there were issues, I would expect more "show stopper" type ones. As I noted above, if issues did occur, they would be more likely to occur under LXC, rather than in a "proper" VM. As you're likely aware, LXC is tied much more closely to the host, where KVM provides full virtualisation of hardware. If a KVM related issue did occur, this seems like a very strange one.
Regardless, I'll aim to try again with the ISO later today and report back. I have intended to update Proxmox too, but I won't commit to getting that done in the next few days.
If you do get a chance, please try a fresh install to a new VM and take note of anything that strikes you as unexpected, weird or any error messages. Once its installed and first thing after you've rebooted into the system, please post the full journal output. It'll likely be quite long, so perhaps better to add it to your OP as an attachment (let me know if you do that, as it won't show up by default - dumb website bug that I've never worked out).
Very strange. I'll test the ISO too.
Sorry I should have read your OP properly... You did already say it was v18.0! Next I was going to suggest that perhaps it got some minor corruption, but you've also ruled that out.
Different to you, I installed the v18.0 LXC template on Proxmox. Although It should not make any fundamental difference - as we create the LXC templates from the ISO. So other than a few specific tweaks required for LXC, they should be essentially the same. FYI I downloaded the LXC template via the "Proxmox Templates" in the web UI. If there were issues, I would expect them to be more likely under LXC, not the other way around.
As you're running the latest Proxmox, that is another difference - I'm still running the older v7.x. But again, I would not expect that to cause any fundamental difference in this case. While newer versions of packages on the host may cause some different behavior in guests, if there were issues, I would expect more "show stopper" type ones. As I noted above, if issues did occur, they would be more likely to occur under LXC, rather than in a "proper" VM. As you're likely aware, LXC is tied much more closely to the host, where KVM provides full virtualisation of hardware. If a KVM related issue did occur, this seems like a very strange one.
Regardless, I'll aim to try again with the ISO later today and report back. I have intended to update Proxmox too, but I won't commit to getting that done in the next few days.
If you do get a chance, please try a fresh install to a new VM and take note of anything that strikes you as unexpected, weird or any error messages. Once its installed and first thing after you've rebooted into the system, please post the full journal output. It'll likely be quite long, so perhaps better to add it to your OP as an attachment (let me know if you do that, as it won't show up by default - dumb website bug that I've never worked out).
To export the full journal to a file: