iScreensaver and macOS 10.15 Catalina
macOS 10.15 Catalina is scheduled to be released this fall. At the present time, only a developer's beta is available and is under NDA. We are investigating compatibility.
Please note that others have reported that the first developer's beta of Catalina is "definitely rough and not just for screensavers. Roughest macOS initial beta in years..." and "...wait for Catalina beta 2".
See https://github.com/JohnCoates/Aerial/issues/801 for a discussion of another macOS screensaver having trouble in Catalina (this has nothing to do with iScreensaver, but is just an example of the general screensaver problems in Catalina Developer Beta 1).
We'll be posting information in this discussion thread as it develops.