[macOS] KeyPress doesn't react on short inputs for some keys

[inhalt120g]

In the following example, if I hit Cursor Up and release it, the "up" is constantly printed in the console until I hit Cursor Up again.
<?xml version="1.0" encoding="iso-8859-1" ?> <ZApplication Name="App" Caption="ZGameEditor application" FileVersion="2"> <OnUpdate> <KeyPress Keys="^"> <OnPressed> <ZExpression Expression="trace(&quot;up&quot;);"/> </OnPressed> </KeyPress> </OnUpdate> </ZApplication>
It works as expected if I hit Cursor Up, hold it for a second or more and then release it.