Hi,
Thanks for the report.
We got a similar issue on the configuration few months ago but it looks like I forgot to propagate the patch in the vendor edition !
In the view "backend / vendormarket / options" (or file "administrator/components/com_hikamarket/views/vendormarket/tmpl/options.php") please replace
echo $this->categoryType->displayMultiple('data[vendor][vendor_params][extra_categories]', explode(',', @$this->vendor->vendor_params->extra_categories));
By
echo $this->nameboxType->display(
'data[vendor][vendor_params][extra_categories]',
explode(',', @$this->vendor->vendor_params->extra_categories),
hikamarketNameboxType::NAMEBOX_MULTIPLE,
'category',
array(
'delete' => true,
'root' => 0,
'sort' => true,
'default_text' => '<em>'.JText::_('HIKA_NONE').'</em>',
'force_data' => true
)
);
And it will fix your saving issue.
Regards,