Why the text in the text box of lettering properties is grey-out when opening a lettering design EMB file from the third party?

Scenario:

An EmbroideryStudio e4 user received a lettering EMB file from a third party. When this user tries to edit the text in EmbroideryStudio e4, the text in the text input box is greyed-out. It will however allow them to reshape.

Explanation: 

This is because the lettering font file is from a third party.  

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If you duplicate this lettering object and change it to another font. Then try to apply the previous font back. Note: there is no "Channel Stardaard" font in the list. Therefore, it is from a third party. 

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In e3, it does not show the font name at all if the font is from a third party.

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Of course, if this EmbroideryStudio e4 user has this "Channel Stardaard.esa" file in the WLETTER folder, then it behaves just like a normal Wilcom font.