Unable to save a custom report in Google Analytics 4.

After setting up an include hostname filter to restrict the Tech details: Operating system report to three subdomains, I encounter an error message stating "The report couldn't be saved" when attempting to save it. Additionally, in the Chrome console, I notice a "Failed to load resource" error with a server response status of 500.

Actually, that error message seems to be a bug because all client reports are getting saved. Do check your library for the same, that's where I found my reports.

Hope this helps!