Tested with Public beta 5
It was fixed in developer beta 6 for my application which exhibited the same behaviour you describe.
As to public betas, this is what OSX Daily says:
Apple has released MacOS Catalina 10.15 beta 6 to those who are enrolled in the developer beta testing program for macOS system software. Typically a developer beta arrives first, soon followed by the same build as a public beta release yet versioned a number behind. MacOS Catalina beta 6 would be MacOS Catalina public beta 5. Dev beta 6 carries the build 19A536g.
So I'm not sure why you still have the issue - note that my application was generated with Lazarus trunk and FPC trunk.
The Catalina beta road has been somewhat bumpy so far. I find it, even as a mere hobbyist, worth paying Apple their $US 99 for developer status which includes two "free" Technical Support Incidents (one of which I have used to discover how non-Xcode generated command-line executables could be notarised).