Items not selectable on invoices/bills

Hi, since the last update (on-premise installation; 3.1.11, German language selected) I cannot select all of my items for bills/invoices.
Only the first (prefetched) list of 10 items are selectable; on entering phrases to the search field the list does not get updated from the database and just filters on the prefetched items.
Does anyone else have the same issue? How can this be solved?

I already cleared browser cache aso., used different browsers/browser versions.

Kind regards, Alex

Researching on issue (using Debug logging) I found out it is caused by returning a NULL value in "getColorHexCodeAttribute()" in Model "app/Models/Setting/Category.php".
I currently am not using categories for my items. I did fix it by createing a NULL handler for the function call but this should be fixed in the next version.