Field filter on SQL server synonym

I want to use field filters.
But, it seems metabase doesn't factor in synonyms to other database, within my current one.
We are using SQL Server

I am querying my synonyms pointing to our data warehouse. This is just 2 tables, containing mostly id's and information that we want to present in a dashboard.

The synonyms are on a snapshot of our main database, where the more detailed information is contained in. (I am querying from here)
And would like to put a field filter on a timestamp on one of those synonyms but it my field doesn't show up in the field filter field options.

I am already querying it, with an sql query so I am getting data from it, but the field filter doesn't seem to work.

Is this maybe a setting I can flick somewhere, or is this not yet implemented?

edit
This sadly also prevents me from using linked filters, because I am unable to define the relationship in the admin panel since the tables don't appear

Can you post diagnostic info and also the queries? thanks

There isn't anything going wrong per-se. I just need interface options I don't have.
SQL server has these synonyms to alias to a different database. But I don't see these tables in my admin panel. I see all my other tables in t1, but not the synonyms that point to the datawarehouse, t2.

FROM dwBdgtAdmnstrtn AS relation
LEFT JOIN rdLctn ON rdLctn.id = relation.lctn
LEFT JOIN crmRltnGrp ON crmRltnGrp.id = relation.rltnGrp

dwBdgtAdmnstrtn is the synonym. I am joining 2 tables from the database the synonyms are on. (t1)
rdLctn and crmRltnGrp

I need the admin options, because I need to define the relationship between these tables close so that I can use linked filters.

I want relation to influence the options in the dropdown for relationgroup. For that (to my knowledge) I need to define relationship correctly.

Thanks.

I've got linked filters working now, had to do some reading up.
So it's not an issue anymore, but it might be something nice to have down the line