The spreadsheet currently relies on the <v> tag and doesn't accept cell type "inlineStr". Here is an article with more info regarding the inlineStr type:

https://c-rex.net/projects/samples/ooxml/e1/Part4/OOXML_P4_DOCX_c_topic_ID0E1XM4.html 

A cell of type "inlineStr" which is currently not accepted in SpredSheet

<c r="F2" s="4" t="inlineStr">
        <is>
          <t>1005131528</t>
        </is>
      </c>

while the format saved from excel is accepted:

<c r="F2" s="2" t="s">
        <v>12</v>
      </c>

Ticket ID: 1517963