Hi!
I followed your advice and made a report to my local reseller who made a report to Graphisoft.
I get a response from Graphisoft :
The ID of the macro "Simple door opening" changed in AC18 :
"ADDD8615-ABD0-4E9D-8EE4-EBD7DAC87CF4" --> "F6FAB810-3A56-4C74-8EB8-B58738A9EE9B"
To fix the object, open it in AC18 and save it unchanged. That's it !
It works but the object is no longer compatible with AC16 ...