Given it was working with 5.0.3 and isn’t now, you may want to file a bug report with Best Practical.
Looking in the upgrade notes for 5.0.4, the only change that jumps out as relevant is the WebSecureCookies change.
Given it was working with 5.0.3 and isn’t now, you may want to file a bug report with Best Practical.
Looking in the upgrade notes for 5.0.4, the only change that jumps out as relevant is the WebSecureCookies change.