No argument to takeScreenshot() ?
How the document says?
https://docs.katalon.com/katalon-studio/docs/webui-take-screenshot.html#example
Wow, the document says that the 1st argument fileName is optional. — I did not know it. I always specified the fileName argument.
@romeo.nacario
How about trying to give fileName parameter explicity? That may work.
See also
@ThanhTo
@devalex88
@romeo.nacario says WebUI.takeScreenshot() worked in v6.3.3, but does not work in v7.0.3. This is a bit smelly, I think.