import cache doesn't work for a date cell

Steps to Reproduce

1. import resume.xlsx with import cache enabled

    <library-property>
        <name>io.keikai.import.cache</name>
        <value>true</value>
    </library-property>

2. check C4

Current Result

#REF!

Expected Result

1978/3/15

Debug Information

other cells that have cached result display values as expected.