The issue is caused because Lazarus creates a app bundle with a link in it. And some (newer) gdb, have a bug, and resolve that link, instead of calling the link.
I doubt 1.0.8 will help.
The old apple gdb 6.3.50 could open the app bundle itself (like you would open it in the finder)
The new gdb all need the actual exe in the bundle.
For The OS that is ok, as long as the exe is in the bundle. But if the exe is not in the bundle, then the lack of intractability will be there.
Lazarus creates project.app/MacOs/Content/project But this is a link. And the real exe is not in the bundle.
When GDB is given that link, it should use that link, and pass the link to the OS. But some GDB do not, the resolve the link, and pass the exe outside the bundle.
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Solution
In Project options, change the final exe name and location, to actually be in the bundle.