Hi Engin,

This is an issue with the SQL Database Collation, that can be changed for Server-Side processing tables such as SQL Tables.

For example, if your Table search or filtering is case sensitive and you wish it to be 'case insensitive',

go in your WordPress SQL Database via PHPMyAdmin or any other DB management Tool, ( you can ask your hosting for help if you are not sure how),

and there, you can change your Database Collation to any 'case insensitive' one, then the Table should search/filter as case insensitive.

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When it comes to special character filtering, i am not able to reproduce this issue on your Table.

If i try to search any value i can see from the Cells, such as for example "İngilizce" the Column filter works :

Or this "Sözlüğü"  , that one also works when being searched in the Filter.

But if you can reproduce the issue as you described, I will advise how you can change your DB collation,

 this is not related to our Plugin, but it is related to which Database Collation you are using on your WordPress Database.

 In our tables, we set up a case insensitive and accent insensitive Database Collation, 

so any search we make on a Table will return results with and without accents. 

For example,  if there is a value as “André” with the special character on é and another first name also as “Andre”,   with regular letter 'e',

we can search in this table and get both returned if we search for “Andre” or “André”.

You need to check in your WordPress Database, what is set for your Collation, 

and choose any that is accent insensitive. 

For this test today, we are using utf8mb3_general_ci collation on our Table, 

and it works as an accent insensitive search; 

but you can search online about this topic and you can easily find various tutorials which Database collations are accent insensitive. 

For example, in this Post from Stack Overflow someone asked which are case insensitive and accent insensitive Collations, 

and they got a good answer. In short, the CI in DB Collations stands for “Case Insensitive” and AI for “Accent Insensitive“. 

Let me know if that helps.