Issue with 'my dashboards' counter


on one installation we have a strange issue. We upgraded from 7.x to 10.0.1. we used synolia dashboard manager in the past. All seems to work as expected except one minor detail. If we go to the dashboard manger as a standard user and remove the module filter and we click on the counter to see how many dashboards we have it shows the count of all dashboards. In this case around 1900

but when I hit the 'show more dashboards' we only get around 21 dashboards back and the counter adjusts accordingly. We don't have any customizations on the dashboard manager or the module api's so I was wondering what could be the cause of this? Or is this a known 'bug'? On other modules I don't seem to have that issue.