HI Andrea, I think your issue relates to trying to filter one dimension where the view has two on the rows.
I think a better approach would be to update the MDX of the view itself to then filter on the combination of OFFERTE and the other dimension.
In my basic sales model where I may have comments against a combination of Customer and Product, I would want to filter on the contents of the cell that is related to both elements that make the combination.

Assuming I want to filter for a Customer/Product combination to show rows where the Comment field contains a particular string, I could use the following MDX:
SELECT
{
[Sales Measures].[Sales Measures].[Units],
[Sales Measures].[Sales Measures].[Comments]
} ON 0,
{ FILTER(
{ DISTINCT( {
TM1SubsetToSet([Customer].[Customer],"Leaf Elements","public")
}*{
[Product].[Product].[Total Products^700201]
})
}, INSTR(1 ,
[Sales Measures].[Sales Measures].[Comments] ,
[User Preferences].(
STRTOMEMBER("[}Clients].[" + UserName + "]"),
[User Preferences].[Free text search]) , 1) > 0) } ON 1
FROM [Sales]
WHERE (
[Scenario].[Scenario].[Actual],
[Period].[Period].[2024-JAN])
If I then update the value of my Free test search field in my User Preferences cube to "caps" I get the following:

Based on your case, you may want to switch the parameters of the INSTR to suit your search string and your substring being searched for.
You may also need to filter blanks etc. but hopefully this gets you closer...