Sorry for my mistake,
This issue will be fixed in v8.1.0. v8.0.5 doesn’t include the fix.
In v8.1.0, you don’t need to use the workaround in CalculatorWithWorkaroundTest and the test case CalculatorTest will run OK.
For now, you can try v8.1.0.beta at https://github.com/katalon-studio/katalon-studio/releases/tag/v8.1.0.beta