Also tried v8.4.4 > v8.4.4 and this also imports with no error but the stack is not editable and when dragging an imported stack on to the page there is nothing in the stack. The XML files shows the exact same import data for the same stack from either v8.1.0 or v8.4.4. I would expect the XML data is good since the export was done from v8.4.4 and the import was done from v8.4.4.
I tried it with a single very simple Stack. Same results. Here is the XML:
<?xml version="1.0" encoding="UTF-8"?> <concrete5-cif version="1.0"> <stacks> <stack name="Vertical 50 Spacer" path="/vertical-50-spacer"> <area name="Main"> <blocks> <block type="html" name=""> <data table="btContentLocal"> <record> <content><![CDATA[<div style="margin-top:50px"></div>]]></content> </record> </data> </block> </blocks> </area> </stack> </stacks> </concrete5-cif>