Ok, I believe the issue can be re-produced. In this project the BO.pas unit has the logic to compute a hash.
The attribute works when the unit is part of the project.
When the unit is not part of the project but gets found on the search path it does not compile with the attribute and the decorator must be used.
frmAsyncHashU.zip (7.2 KB)
For anyone else watching this tread I removed the posts that do not add value as I have now provided a minimal sample