Changing bg on nav bar open

Hey all - have a weird bug I THINK relates to interactions on navbar.

Seems to work fine when previewing, but when I test it on an actual mobile device I get an issue.

Basically I need to change the colour of the wedge under the navbar (red for test purposes) when opening the menu.

As I say, I’ve achieved this through interactions and it works when previewing, but not on an actual mobile device.

It’s almost like my device is too slow to respond/refresh to the changes the interactions are making.

See link below.

If anyone has any fixes (or an idea of how I can achieve the same thing) I’m all ears.