Any way to avoid "Access policy evaluation is already in progress for your current session." when multiple tabs are opened?

We're in the process of moving from an authentication flow that was highly customized and used an external login form that was presented before Access Policy evaluation started to one that uses more standard APM flows and the standard login form (albeit with heavy styling).

One big backwards step this presents for us is that under some circumstances, users will be presented with an "Access policy evaluation is already in progress for your current session" error where before they'd been presented a login page. In particular this happens when:

• Multiple tabs to resources requiring authentication are opened before a session can be fully established
• The browser makes a background request to one authenticated resource before requesting a different authenticated resource because of explicit user action (this happens especially with Safari's "Preload top hit in background" setting enabled.

There doesn't seem to be anything we can do about this, but before we give up, does anyone have creative solutions to this?