no arrow seen when overflow-y is set

[vtarelkin]

having many items in popup with overflow-y enabled and fixed height makes pointing arrow invisible

Version

"reactjs-popup": "^2.0.4"

Test Case

cannot create cause

 "We were unable to fork the sandbox
You need to sign in to create more than 3 sandboxes"

and it ignores my styles (what am I doing wrong?)

https://codesandbox.io/s/n5q4zqw2n0

Expected Behavior

arrow is visible with overflow set to scroll or auto

Actual Behavior

arrow is hidden