User Form, On every submitted entry, receive an error "Invalid Property Value"

Dear Team,

I am having the below error when I click on Submit button ,

It allows me to go further only when iclick a value in combo button named as "Motif Transfert"....

Here is the following code;

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I suspect that the issue is going to be in the MatchRequired property of the combobox is set to True. IT might be easier for us to help locate the issue if you attach a sample workbook with the userform and code.