After the upgrade to 5.4.0 "Managed FortiAPs" GUI is unresponsive

[infosar]

After the upgrade to 5.4.0 "Managed FortiAPs" GUI is unresponsive

We have two 800c units in failover cluster with 70 FortiAPs in a "Wifi" VDOM, exclusive for FortiAPs. After upgrading from 5.2.4(701) to 5.4.0(1011), The "Managed FortiAPs" link in the web gui becomes totaly unresponsive. When clicking on that link, the page is not rendering anything, it stays blank not displaying the FortiAPs.

We've tested with Firefox, Chrome, IE and MS Edge, the issue persists on all browsers.

Some months ago we updated from 5.2.4 to 5.2.5 and we needed to downgrade because of that same problem. We thought version 5.4.0 would've fixed this but it didn't.

Any help or tip is welcome, thanks in advance!

Best regards,

[localhost]

At first I thought we had the same problem. But then I realized, it just takes a very long time to load the content.

17sec for just 25 APs on our installation.