Direct Query wont display all rows (as it should)

Hi, 

I have the following issue with using a direct query, it seemed to work fine at first, BUT after proper testing, I discovered a strange thing.
My table visual, which was set to display 14 columns with about 2274 rows displayed correct totals BUT when looking at rows, it was missing some lines. Below I display a print screen. In the database, there are 5 orders with 16 lines from customer 10017 . However, when I display all rows, without any filter, it seems to display only 3 orders (picture NOT OK). 

I did some testing and found out, that if I delete the column 'employee comments'  it is working fine (picture OK).

The fact is, that I use Direct query via Native Query from SAP B1 (the result is 2.5k rows in 20 columns). 'Employee comments' was in BLOB format, which I changed via , CAST (T0."U_ZEDS_EmpComments" AS VARCHAR(300)) AS "EmpComments" in native query. The BLOB column was braking refresh in Service (not desktop) so I changed it to VARCHAR(300).  Now the refresh works, but without displaying all lines .... this happebs only in service BTW, desktop seems fine.  

I am really curious about this...  I would expect a refresh/visual error, but not show incomplete lines. This is very dangerous and undermines the reporting. I can try to use VARCHAR(100), but I am not sure if it fixed the problem 100%... 

Could somebody please advise? I could not find any good info about this in the documentation...

Cheers!