Hello @hoborg91,
If we change the name 'circle' by the short name of interface '()':
namespace Something_2_OK {
class MyClass
() IMyInterface
IMyInterface -- MyClass
}
Or if we use directly the 'Lollipop interface' '()--':
namespace Something_3_OK {
class MyClass
IMyInterface ()-- MyClass
}
we observe the expected result:

See also: 'Lollipop interface' on https://plantuml.com/class-diagram
If that can help,
Regards,
Th.