Steps to reproduce:

1. Change configuration of user macro used in LLD Filter expression with some mistake ( for example if you forget to escape backslash on terminal server filter - You use C:\Users instead of C:
   Users)
2. check result of LLD - See first screenshot LLD_error.png

Result:
See screenshot... LLD_drives.png
Discovered Items are marked for deletion and are deleted after Keep lost resources period.

Expected:
Discovered Items are left untouched. Only discovery rule shows error.