Hi @Nikoleos I have not tried this but ideally you should not try to forcefully upgrade the security patch… Especially in your case the Note 5 if I am not wrong is code named whyred and has Anti Roll Back implemented. There is a very good chance you may brick your phone.
On the security patches we are working on providing security patches to all phones including those not being supported by Lineage. Please wait for we should be able to implement this soon.
I have read your message after already updating firmware, but updating it don’t set up to date the vendor security patch, it is still may 2018, so it does nothing without it, /e/ works just fine although