Created attachment 150727 [details]
A simple pivot table with filter on mixed-type content
In the attached spreadsheet, week # is used to filter data in the pivot table (page field). Excel sets cell B1 data type based on which data type was in the data source; so when selecting week 1, =FORMULATEXT(B1) returns TRUE, and for week 2 (which is made text in the data source) it returns FALSE. Using B1 in LOOKUP also succeeds for week 1 when searching over numbers; but fails (correctly) for week 2.
In LibreOffice, the type of B1 is unconditionally text. LOOKUP fails for any week used in the filter.
See https://ask.libreoffice.org/en/question/190242 for real-life problem because of this.
It happens also with dates, may be some relation, as example dates in GETPIVOTDATE() must be introduced as text in the criteria.
Version: 18.104.22.168 (x64)
Build ID: aecc05fe267cc68dde00352a451aa867b3b546ac
CPU threads: 4; OS: Windows 10.0; UI render: GL; VCL: win;
Locale: es-ES (es_ES); UI-Language: en-US