Good to know, thanks.
One could build an AdvancedFilters plugin with this workaround e.g.
AdvancedFilters - Plugin for "Writ voucher count" filters
Attention:
You need to use the AdvancedFilters beta version 1.5.0.6 or higher in order to let this plugion work properly!
You can get the beta version here:
https://www.esoui.com/downloads/info....html#comments
Most current beta version link:
AF beta 1.5.0.6