It is a long running issue with modules, site and generally is caused by a user logging into a DotNetNuke website that then calls on a page (usually on a dotnetnuke child) website that references a separate .aspx web page.
Most often this is caused by the use of some java script that references external .aspx files in the script.
While in an ideal world this would not cause a logout issue for DNN users, especially admin users. It does and in our most recent experience with this was an updated website that used the cute soft “cute editor”.
This editor was working on dotnetnuke 4.9.5 sites, but due to it’s configuration and changes to the DotNetNuke 5x standards. No child portal would support it’s out of the box configuration after upgrading to dnn 5.6.0.
The fix was to throw it away and use the Telerik RAD editor. Not a bad option as far as the users are concerned, but disappointing that this apparent “bug” which we know could be addressed easily has never been identified and solved.
More time wasted!