I found the issue. Because you store everything as a JSON formatted string, when you try to migrate the website JSON breaks.
Your theme would greatly benefit from a fix there as more and more website switch to a multiple stage deployment process. Especially that when you export/import this is from different installation so we’ll need to change urls at some point.
If some of you are stuck with this, the workaround here is to don’t forget to update the property length when you edit something.
for example :
[…]s:4:”logo”;s:50:”http://oldurl.ltd/content/uploads/2014/08/logo.png“[…]
will become
[…]s:4:”logo”;s:55:”http://www.new-url.ltd/content/uploads/2014/08/logo.png“[…]