SAS still isn't reading a TIME column back in as a Numeric time value if any of the values in that TIME column are missing (blank). It assigns the entire column as Text. I'll try a few more output options...
Got around the missing TIME values by adding this code to force a 00:00 time value into the field if the time is missing, before writing it to Excel. That field now correctly IMPORTs from Excel back into SAS as a Time field.