Dear All, Thank you kindly for the replies and concerns over the problem I've experienced. I really appreciate them.
I do not know how often the I -> F conversion is done in CCP4i's F2MTZ GUI, especially with the FreeR flags preserved. Nevertheless, as mentioned, the problem seems to arise because [c]truncate does not recognize the FreeR column, unlike old-truncate. Whether this is a bug or new feature, it would be great if [c]truncate is (re-)programmed to recognize the FreeR column for a more streamlined import/I -> F conversion/uniqueify process executed in F2MTZ. Also thanks for pointing out a relatively straight forward workaround using cad. Best, Peter