Incidentlist: Selection "Show n rows per page" not ok

in on project containing 6 incident be discovered a strange behavior:

till the selection was set to "show 15 rows per page" it was impossible to

display all incident in the list event after having cleared all filters.

The header line always displayed:

Displaying 1 - 4 out of 6 incident(s) for this project

as if a hidden filter were still set.

In the project home > incident summary the incident were "reachable" by clicking on the different counter

that indicate how many incident are available in the different states

Then we set the next higher value: "show 30 rows per page" all incident where displayed.

This is a strange workaround, "request 30 then get 6, request 15 and get 4 ????