Just tested it with Lazarus 2.1.0 r61037M FPC 3.0.4 x86_64-darwin-cocoa (alpha) under macOS Mojave 10.14.4.
I can confirm your finding.
You project produces an Access Violation when assigning a boolean to the enabled property.
I've tried it with a straight "false" as well, and that caused the same error.
I just tried updating from svn, but cannot get the IDE compiled with the latest version;
...
application.inc(560,13) Warning: Symbol "AppHandle" is not portable
Assembling (pipe) units/x86_64-darwin/forms.s
controls.pp(3099,3) Note: Local variable "LastFrm" is assigned but never used
Assembling (pipe) units/x86_64-darwin/controls.s
controls.pp(4648) Fatal: Internal error 2013121801
Fatal: Compilation aborted
make[1]: *** [alllclunits.ppu] Error 1
make: *** [lazbuild] Error 2