Hi,
I’m experiencing heat issues when my laptop (Dell Precision 5520) lid is closed (see psenor temp screenshot).
My setting are:
- Suspend disabled:
sed -i -e 's/HandleLidSwitch=suspend/HandleLidSwitch=ignore/' /etc/systemd/logind.conf && systemctl restart systemd-logind
sudo systemctl mask sleep.target suspend.target hibernate.target hybrid-sleep.target
- Tweaks > Power: Suspend when laptop lid is closed
Is there a fix or it it a known issue?

Sounds like a kernel issue.
Please report a bug on launchpad by running the following in a terminal:
ubuntu-bug kernel
The triagers are likely to ask you to try the latest upstream kernel either 4.16 or 4.17. They will give you instructions on how to-do this.
Note - if you didnt say to purge all obsolete packages after the upgrade the 17.10 4.13 kernel will still be available via grub - so you could also test with this and add this info to your bug report.