I am able to get in to the collection now, it seems the simple fix was to have the "Remember Me" box CHECKED. This appears to have resolved the repeated login screen loop for me.
Same issue for me, I've tried the above steps, using chrome, ensured I was logged in, cache cleared, different devices, adblockers off, etc... also directly to http://ignition.customsforge.com and http://ignition.customsforge.com/search/collection.... it just brings me back to the login page and it shows me logged in at top left of screen. Wash, rinse, repeat.