Description:
Calc blocks you from filtering for only lines with empty cells in a column, when certain filters are used in other columns.

Steps to Reproduce:
1. Setup a spreadsheet with e.g.:
a,b,c
x,d,
y,,e
z,,
2. Add autofilter (ctrl+shift+l)
3. In column c, show only empty values
4. In column b, try to show only empty values

Actual Results:
When trying to set filters for column b, the value "(empty)" is grayed out. If you deselect "d", "Ok" will be grayed out.

Expected Results:
Only rows with empty values in column b and c shown (i.e. row "z")


Reproducible: Always


User Profile Reset: Yes

Additional Info:
Version: 24.2.1.2 (X86_64) / LibreOffice Community
Build ID: 420(Build:2)
CPU threads: 16; OS: Linux 6.7; UI render: default; VCL: kf5 (cairo+xcb)
Locale: sv-SE (sv_SE.UTF-8); UI: sv-SE
Calc: CL threaded