My guess is that it is a permissions issue on the ArchiCAD Library 18 folder or the enclosing directory. Given that your ArchiCAD Library 18 is in the default location (/Applications/GRAPHISOFT/ArchiCAD 18/ArchiCAD Library 18), try the following:
a. Quit ArchiCAD.
b. Go to /Applications/ folder and highlight
GRAPHISOFT folder
c. Press
CMD +
I or right-click and choose
Get Info
d. In the window that appears, under
Sharing & Permissions set all listed names to
Read & Write
e. Unlock the padlock icon at the bottom of the dialog
f. Click the Settings button (looks like a gear or a cog)
g. Choose
Apply to enclosed items and then confirm.
h. Re-open ArchiCAD and see if the problem remains.
I hope this helps.
Best regards,