@jorbian
Try this.
Go to file:
oc-content/plugins/list_seller_items/index.php
Find code:
if(osc_get_preference('rewriteEnabled', 'osclass') <> 1) {
Replace with:
if(osc_get_preference('rewriteEnabled', 'osclass') <> 1 or 1==1) {
Note that this is problem related to plugin that we do not sell and therefore no further help will be provided.