I am also looking to find a solution on this.
You who solved it, what did you do?
Lots of trial and error. Check that the CMS is using a separate cookie to store login persistence as that was part of my problem on a shared server. Someone else on here can no doubt help you out with that more than me - I had to call in a favour from a mate who is great at going through code line by line to find the problem (I’m far too impatient). Good luck - I hope you can get it sorted out.