"Clear" option in Assessment part works only in Draft according to the following rule:
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I. For Grade:

1. System set the grade for this item from template - if it was specified for this item

OR

2. System uses the default grade for that template
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II. For Status, Risk, Solution, Budget or Custom text field:
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​1. System clears the fields - for those one who have no predefined marked as "Default" value
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2. System clears the fields and fill in with default values - for fields, which have predefined values marked with a little checkbox near it:
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III. For Location

System leaves the location unchanged (if you need to change it - do it manually).
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​IV. For all the other fields

System clears the values.