[chirp_users] FT-450D communication problem

I have just downloaded latest Chirp (CHIRP daily-20180906).

Using Windows 10, Com port 3, Vendor Yaesu, Model FT-450D.

My CAT cable works fine with "PCC for FT-450D", WSJT-X , "Ham Radio Deluxe" & "FREE450", but not "Chirp"!

Followed instructions to download from radio & got message:-

An error has occurred - Failed to communicate with radio: Unable to read block 0 expected 6 got 4.

Any ideas?

My FT-450D has the UK 60m frequencies plumbed into the memories - will these be saved in Chirp? I want to update the radio's firmware, so want to backup the memories including the 60m ones.

Thanks